Intensive Voice Treatment (LSVT LOUD) for Children With Spastic Cerebral Palsy and Dysarthria Purpose The purpose of this study was to examine the effects of an intensive voice treatment (Lee Silverman Voice Treatment, commonly known as LSVT LOUD) for children with spastic cerebral palsy (CP) and dysarthria. Method A nonconcurrent multiple baseline single-subject design with replication across 5 children with spastic ... Research Article
Open Access
Research Article  |   June 01, 2012
Intensive Voice Treatment (LSVT LOUD) for Children With Spastic Cerebral Palsy and Dysarthria
 
Author Affiliations & Notes
  • Cynthia Marie Fox
    National Center for Voice and Speech, Denver, CO
  • Carol Ann Boliek
    University of Alberta, Edmonton, Alberta, Canada
Article Information
Speech, Voice & Prosodic Disorders / Dysarthria / Voice Disorders / Hearing & Speech Perception / Acoustics / Special Populations / Genetic & Congenital Disorders / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   June 01, 2012
Intensive Voice Treatment (LSVT LOUD) for Children With Spastic Cerebral Palsy and Dysarthria
Journal of Speech, Language, and Hearing Research, June 2012, Vol. 55, 930-945. doi:10.1044/1092-4388(2011/10-0235)
History: Received August 24, 2010 , Revised March 4, 2011 , Accepted October 19, 2011
 
Journal of Speech, Language, and Hearing Research, June 2012, Vol. 55, 930-945. doi:10.1044/1092-4388(2011/10-0235)
History: Received August 24, 2010; Revised March 4, 2011; Accepted October 19, 2011
Web of Science® Times Cited: 32

Purpose The purpose of this study was to examine the effects of an intensive voice treatment (Lee Silverman Voice Treatment, commonly known as LSVT LOUD) for children with spastic cerebral palsy (CP) and dysarthria.

Method A nonconcurrent multiple baseline single-subject design with replication across 5 children with spastic CP was used. Auditory–perceptual analysis of speech, acoustic measures of vocal functioning, and perceptual ratings by parents of participants were obtained at baseline, posttreatment, and 6-week follow-up recording sessions.

Results Listeners consistently preferred the speech samples taken immediately posttreatment over those taken during the baseline phase for most perceptual characteristics rated in this study. Changes in acoustic measures of vocal functioning were not consistent across participants and occurred more frequently for maximum performance tasks as opposed to speech. Although parents of the treated participants reported an improved perception of vocal loudness immediately following treatment, maintenance of changes at 6-week follow-up varied across the participants. No changes were observed in the 5th participant, who did not receive treatment.

Conclusions These findings provide some preliminary observations that the children with spastic CP in this study not only tolerated intensive voice treatment but also showed improvement on select aspects of vocal functioning. These outcomes warrant further research through Phase 2 treatment studies.

Speech disorders have been reported to occur in children with spastic cerebral palsy (CP; Workinger & Kent, 1991); however, reliable prevalence figures have not been documented (Pennington, Miller, & Robson, 2009). The most common perceptual characteristics include consistent hypernasality, breathy voice quality, monotonous speech, reduced loudness, and uncontrolled rate and rhythm of voice (Workinger & Kent, 1991). Disordered respiration characterized by short vowel durations, shallow inspirations, and forced expirations also has been reported (Clement & Twitchell, 1959; Solomon & Charron, 1998). In addition, disordered articulation has been described in these children (Clement & Twitchell, 1959; Hixon & Hardy, 1964). There are limited efficacy data on speech treatment for children with CP; hence, there is a great need for research in this area (Pennington et al., 2009).
Advances in clinical neurorehabilitation have documented key elements of motor learning and principles that drive activity-dependent neuroplasticity (i.e., modifications in the central nervous system in response to physical activity), such as intensive treatment, repetitive active practice, and sensory feedback associated with movement. These elements may have merit in the context of successful treatment paradigms for adults and children with neurological disease or impairments (Garvey, Giannetti, Alter, & Lum, 2007; Kleim & Jones, 2008; Kleim Jones, & Schallert, 2003; Maas et al., 2008). Moreover, there is a growing focus in speech treatment research to translate principles of both motor learning and activity-dependent neuroplasticity into protocols for treatment of motor speech disorders in children and adults (Ludlow et al., 2008; Maas et al., 2008).
Previous studies have documented that children with CP are capable of intensive treatment regimes and that initial fatigue may be due to deconditioning effects that often decrease over time (Bower, McLellan, Arney, & Campbell, 1996; Schindl, Forstner, Kern, & Hesse, 2000). Research also has shown that the use of task-specific, repetitive practice and active practice along with increased numbers of practice trials results in marked improvements in gait (Damiano, Kelly, & Vaughan, 1995; Schindl et al., 2000), grip force production (Valvano & Newell, 1998), and anticipatory grip force precision (Gordon & Duff, 1999) in children with CP. In addition, enhanced sensory input and active attention to sensory feedback during practice may facilitate neuroplastic changes of cortical sensorimotor maps, which is thought to foster internal representations for movement important for carryover and maintenance of the new target behavior, such as reaching (Hadders-Algra, 2000; Hadders-Algra, van der Fits, Stremmelaar, & Touwen, 1999; Lenz & Byl, 1999).
Current speech treatment methods for children with CP and dysarthria are varied but typically use a systems approach to address respiration, phonation, articulation, and resonance (Pennington et al., 2009). Recently reviewed observational studies of speech interventions for children with dysarthria indicated that teaching slow, loud speech may be associated with improvements in speech intelligibility, voice quality, and clarity (Pennington et al., 2009). For example, Pennington, Miller, Robson, and Steen (2010)  reported on 16 children with CP and dysarthria who received intensive treatment consisting of three 35- to 40-min sessions a week for 6 weeks, focusing on controlling breath support, phonation, and rate. Improvements were documented in single-word and connected speech intelligibility for both familiar and unfamiliar listeners.
A model of speech treatment, known as LSVT LOUD (Lee Silverman Voice Treatment), has been developed for individuals with Parkinson's disease (PD) and has documented efficacy for that population (Ramig et al., 2001). The training mode of LSVT LOUD is consistent with principles that drive activity-dependent neuroplasticity and motor learning (Fox et al., 2006). LSVT LOUD incorporates enhancement of the voice source, consistent with improving the carrier in the classic engineering concept of signal transmission (Titze, 1993) and using vocal loudness as a trigger for distributed effects across the speech production system (Dromey & Ramig, 1988; Sapir, Spielman, Ramig, Story, & Fox, 2007). The extent to which the effects of LSVT LOUD are specific to hypokinetic dysarthria is not clear. However, positive outcomes in acoustic measures (e.g., vocal sound pressure level [SPL]) and listener perceptions (e.g., articulatory precision) have been reported post–LSVT LOUD from single-subject and case studies of adults with spastic and ataxic types of dysarthria (Sapir et al., 2001, 2003).
The idea of targeting vocal loudness or respiratory–phonatory effort in treatment of dysarthria is not new. Establishing a respiratory–phonatory foundation before addressing other speech subsystems is consistent with approaches recommended for treating motor speech disorders that (a) create a single-motor organizing theme, (b) have a maximum impact on other aspects of speech production, and (c) increase effort across the speech mechanism (Duffy, 1995; Rosenbek & LaPointe, 1985; Yorkston, Beukelman, & Bell, 1988). Moreover, it has been recommended that treating respiratory–phonatory support for speech should occur first or at least co-occur with any focused articulation treatment in children with motor speech disorders (Strand, 1995). The unique aspect of LSVT LOUD is the singular target of training healthy vocal loudness (respiratory–phonatory effort) to the exclusion of targeting rate, articulation, and resonance.
The singular training target of healthy vocal loudness may be desirable for children with spastic CP. These children have disordered voice characteristics, which may be due to muscle weakness or incoordination of respiratory and laryngeal subsystems (Ansel & Kent, 1992; Workinger & Kent, 1991). The single focus on vocal loudness limits cognitive demands associated with treatment, which may be important for children with low-average to below-average cognitive functioning. Finally, the target vocal loudness trained in LSVT LOUD is elicited through modeling behavior (e.g., “do what I do”), which minimizes explicit verbal instructions and may allow the child's system to implicitly self-organize in order to achieve the goal (Schmidt & Fitzpatrick, 1996). Further, LSVT LOUD addresses criticisms of previous behavioral treatment studies in children with CP, for example, that (a) treatment was not delivered in a standardized manner, (b) dosages of treatment were not discrete, and (c) techniques were often combined (Butler & Darrah, 2001). LSVT LOUD minimizes these issues through a protocol of specific daily exercises prescribed for the entire treatment regime, a finite period of treatment, and a single treatment focus on vocal loudness.
The purpose of this Phase 1 treatment study was to examine any therapeutic effects of delivering LSVT LOUD in children with spastic CP and dysarthria (Robey & Schultz, 1998). The specific questions related to this purpose are as follows: (a) Do listeners prefer posttreatment over baseline speech samples of children with CP on a number of perceptual characteristics of voice and speech; (b) will intensive voice treatment affect the vocal motor system of children with spastic CP and dysarthria as evidenced by changes in acoustic measures of voice; (c) do parents perceive changes in perceptual voice and speech characteristics after intensive voice treatment; and (d) do treatment effects, if any, last over time?
Method
Participants
Five children between the ages of 5 and 7 years with a medical diagnosis of predominantly spastic CP were recruited. Characteristics of each participant are detailed in Table 1. Additional selection criteria included (a) dysarthria; (b) hearing that was within normal limits or aided to normal limits; (c) no vocal fold pathology as determined by an otolaryngologist; (d) ability to follow directions for the study tasks; and (e) stable medications, if applicable. Children with severe velopharyngeal incompetence, structural disorders of the speech mechanism, or a concomitant speech disorder (e.g., stuttering) were excluded. The medical diagnosis of spastic CP was confirmed by review of medical records. The characteristics and severity of dysarthria were determined by consensus of two certified speech-language pathologists from audio and video samples of participants with CP.
Table 1. Participant characteristics.
Participant characteristics.×
Descriptor Participant
P1 P2 P3 P4 P5
Age (years;months) 7;10 5;10 6;1 7;7 6;7
Gender Male Female Male Male Female
Diagnosis Spastic quadriparesis due to CP; secondary seizure disorder Spastic quadriparesis due to CP Spastic quadriparesis secondary to CP Spastic quadriparesis secondary to CP Spastic quadriparesis secondary to CP
Parent-reported speech andvoice concerns “Breathy, quiet voice with weak breath support,” did not have confidence with speaking (e.g., “intimidated by other kids”) Weak breath control, soft speech, “choppy speech” (i.e., took a lot of breaths to finish a sentence) Improving breath control, improving clarity of speech, maintaining loudness and clarity at end of sentences Breath control; quiet, “whispered” voice; short utterances “Take a full tidal breath,” not always having enough breath, stopping in the middle of sentences to get a breath, breathing coordination
Observed speech and voice signs (2 SLPs) Reduced loudness, monotone, intermittent hypernasality, intermittent harshness, imprecise consonants, variable slow rate (task dependent), prosodic abnormalities Variable loudness, inconsistent breathy-harsh voice quality, inconsistent slow rate, whispered at end of sentences, mild articulatory imprecision Variable loudness, irregular articulatory breakdowns, variable rate, strained voice quality with occasional voice stoppages, intermittent glottal fry Minimal voicing, reduced loudness to aphonic, monotone, imprecise articulation, spoke only 1–2 word phrases Variable loudness; variable pitch; inconsistent strained voice quality, especially at end of sentences; mild, imprecise articulation
Dysarthria type Spastic Spastic Mixed spastic/ataxic Spastic Spastic
Overall dysarthria severity Moderate Mild–moderate Moderate Marked Moderate
Study condition Condition A 4 BASE/2 weeks Condition C 5 BASE/5 weeks Condition B 5 BASE/3 weeks Condition A 4 BASE/3 weeks Condition D 4 BASE/3 weeks
Age (years;months), gender-matched control 7;6 Male 6;2 Female 6;1 Male 7;1 Male 7;0 Female
Note.P1 (P2, etc.) = Participant 1 (2, etc.); CP = cerebral palsy; SLP = speech-language pathologist; BASE = baseline.
Note.P1 (P2, etc.) = Participant 1 (2, etc.); CP = cerebral palsy; SLP = speech-language pathologist; BASE = baseline.×
Table 1. Participant characteristics.
Participant characteristics.×
Descriptor Participant
P1 P2 P3 P4 P5
Age (years;months) 7;10 5;10 6;1 7;7 6;7
Gender Male Female Male Male Female
Diagnosis Spastic quadriparesis due to CP; secondary seizure disorder Spastic quadriparesis due to CP Spastic quadriparesis secondary to CP Spastic quadriparesis secondary to CP Spastic quadriparesis secondary to CP
Parent-reported speech andvoice concerns “Breathy, quiet voice with weak breath support,” did not have confidence with speaking (e.g., “intimidated by other kids”) Weak breath control, soft speech, “choppy speech” (i.e., took a lot of breaths to finish a sentence) Improving breath control, improving clarity of speech, maintaining loudness and clarity at end of sentences Breath control; quiet, “whispered” voice; short utterances “Take a full tidal breath,” not always having enough breath, stopping in the middle of sentences to get a breath, breathing coordination
Observed speech and voice signs (2 SLPs) Reduced loudness, monotone, intermittent hypernasality, intermittent harshness, imprecise consonants, variable slow rate (task dependent), prosodic abnormalities Variable loudness, inconsistent breathy-harsh voice quality, inconsistent slow rate, whispered at end of sentences, mild articulatory imprecision Variable loudness, irregular articulatory breakdowns, variable rate, strained voice quality with occasional voice stoppages, intermittent glottal fry Minimal voicing, reduced loudness to aphonic, monotone, imprecise articulation, spoke only 1–2 word phrases Variable loudness; variable pitch; inconsistent strained voice quality, especially at end of sentences; mild, imprecise articulation
Dysarthria type Spastic Spastic Mixed spastic/ataxic Spastic Spastic
Overall dysarthria severity Moderate Mild–moderate Moderate Marked Moderate
Study condition Condition A 4 BASE/2 weeks Condition C 5 BASE/5 weeks Condition B 5 BASE/3 weeks Condition A 4 BASE/3 weeks Condition D 4 BASE/3 weeks
Age (years;months), gender-matched control 7;6 Male 6;2 Female 6;1 Male 7;1 Male 7;0 Female
Note.P1 (P2, etc.) = Participant 1 (2, etc.); CP = cerebral palsy; SLP = speech-language pathologist; BASE = baseline.
Note.P1 (P2, etc.) = Participant 1 (2, etc.); CP = cerebral palsy; SLP = speech-language pathologist; BASE = baseline.×
×
A yoked group of typically developing, sex- and age-matched children was recruited to participate in this study. This allowed for a direct comparison between performance of participants with CP and their matched peers, because data were collected using the same tasks and methodology. The typically developing peers had no known neurological disease or condition and no history of speech or voice disorders. Their ages and pairings with participants with CP are listed in Table 1.
Design
This study used a nonconcurrent multiple baseline design with replication across subjects (Barlow & Hersen, 1984; Watson & Workman, 1981). In this design, the treatment variable (intensive treatment) was applied sequentially to the same behavior (vocal output) across different but matched subjects sharing the same environmental conditions. In a nonconcurrent design, the length of the baseline phase is varied (some short and some longer) and predetermined (Watson & Workman, 1981). When participants became available, they were randomly assigned to one of the predetermined baseline conditions. This provided flexibility for conducting the research within real-world constraints while maintaining the internal validity achieved with a concurrent design (i.e., controlling for history or maturation variables; Watson & Workman, 1981).
Procedures
Participant Selection
A telephone screening questionnaire was completed with parents of potential participants followed by a face-to-face screening session with the child. All the parents signed a consent form, and children signed an assent document agreeing to participate. This study received approval from the University of Arizona Institutional Review Board. The screening session included (a) a brief voice and speech screening, (b) an assessment of abilities to follow directions related to the study tasks, and (c) a hearing screening (500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz at 25 dB HL). In addition, a laryngeal examination was conducted by an otolaryngologist to ensure that no laryngeal pathology (e.g., vocal nodules or paralysis) existed. All five participants completed the entire study.
Study Conditions
Participants were randomly assigned to one of four study conditions with varying durations of baseline phases according to the nonconcurrent study design. A minimum of four baseline recordings were planned across Conditions A (2-week baseline), B (3-week baseline), and C (4-week baseline). Participant assignment to study conditions and the actual number of recording sessions are summarized in Table 1. These conditions all included 16 treatment sessions (4 sessions a week for 4 consecutive weeks), two recording sessions 1 week immediately following treatment (POST), and two recording sessions 6 weeks after the conclusion of treatment (FUP). Condition D matched Condition A except no treatment was delivered. Treatment was administered to the participant in Condition D following the final FUP recording session. The inclusion of an untreated participant with CP was to document potential maturational changes that may occur during the study period and affect interpretation of the results (Stiller, Marcoux, & Olson, 2003).
Recording Sessions
Equipment and setup. Data collection procedures were identical for all baseline (BASE), posttreatment (POST), and follow-up (FUP) recording sessions. Duration of recording sessions ranged from 30 min to 1 hr. Data were collected in an Industrial Acoustics Company sound-treated booth, and all sessions were videotaped. Four of the participants were comfortably seated in their own wheelchairs. One participant sat in an adaptive chair. Audio recordings were made with the participant wearing a small omni-directional condenser microphone (Audio-Technica, Model AT 803b) taped to his or her forehead and secured with a soft, elastic cloth headband. The distance from the corner of the child's mouth to his or her forehead was measured for placement of the microphone at each recording session. This allowed for a constant mouth-to-microphone distance of 4 in. within and across recording sessions. Microphone signals were recorded onto a digital audiotape (DAT) recorder (Panasonic Digital Audio Tape Deck, Model SV-3500). Calibration signals were recorded at the beginning and end of each session by securing the omni-directional condenser microphone and sound level meter (SLM) microphone to a Styrofoam head at a distance of 4 in. from the mouth of the head, mimicking the setup on the child. A tone generator (KORG Auto Chromatic Tuner, AT-12) was placed in the same plane as the Styrofoam head's mouth. The generated tone (960.5 Hz) was recorded to the DAT, and the exact sound pressure level (dB SPL) reading from the SLM was recorded.
Data were collected by four graduate students and the first author, who were well trained in the experimental protocol. The investigator who delivered treatment (the first author) did not collect POST or FUP data. All attempts to keep the student data collectors blinded to the purpose of the study were made; however, there were occasions when the participants revealed aspects of the treatment they received. All data collectors were trained to keep the same demeanor and instructions regardless of the participants' comments.
Voice and speech tasks. The protocol included two maximum performance tasks, including a sustained vowel and maximal frequency range for vowels, as well as a sentence repetition task (Kent & Kent, 2000; Kent, Kent, & Rosenbek, 1987; Rvachew, Hodge, & Ohberg, 2005). For the maximal performance tasks, instructions were “Take a deep breath and say ‘ah’ for as long as you can,” and “Take a deep breath and say ‘ah’ as high/low as you can.” The data collectors were careful to use specific instructions that encouraged maximum performance for duration and frequency range but never gave any specific instructions or cues related to vocal loudness. Multiple repetitions of each task (average of six trials) were elicited during each recording session to ensure that maximum performance was captured (Kent et al., 1987). The speech task involved repeating the sentences “Buy Bobby a puppy,” “The potato stew is in the pot,” and “The blue spot is on the key” three times at each recording session. The instructions were as follows: “I am going to say some sentences. After I say the sentence, I will point to you and I want you to repeat what I say.” Data collectors were careful to model the sentences consistently across sessions and without exaggerated loudness, articulation, or pitch inflection. These sentences were not trained during the treatment phase of the study. The order of presentation of maximum performance and sentence repetition tasks was randomized across all recording sessions.
Parent rating forms. A visual analog scale (Kempster, 1984; Schiffman, Reynolds, & Young, 1981) was filled out by one of the participant's parents at BASE, POST, and FUP sessions. This scale obtained ratings on 10 variables related to voice (loud, nasal, hoarse/scratchy, monotone, breathy, strained), speech (speaks so others can understand), and spoken communication (talks when playing with other kids, starts talking with other kids, frustrated when talking). The scale required the parent to place a vertical slash through a solid horizontal line (15.2 cm) that represented a continuum ranging from continuous presence of a characteristic, “Voice is always loud enough,” to complete absence of a characteristic, “Voice is never loud enough.” Parents were instructed to make their ratings based on perceptions of their child's speech “most of the time” versus their perception on the day of the recording session.
Intensive Voice Treatment
LSVT LOUD treatment consisted of 16 individual 1-hr treatment sessions delivered on 4 consecutive days each week for 4 consecutive weeks. Homework and carryover exercises were assigned every day during the month of treatment. All treatment was delivered by an expert LSVT LOUD clinician (the first author). All treatment sessions were conducted in the participant's home. The first half of each treatment session consisted of three daily tasks: (a) maximum duration sustained vowels, (b) maximum frequency range, and (c) repetition of 10 functional phrases (generated by the participant and his or her family) five times each. The second half of treatment sessions was spent on a speech hierarchy progressing in difficulty from single words to conversational speech. In the case where a child had reduced verbal output (one- to four-word phrases), the progression went from structured to less structured tasks (e.g., naming pictures to playing games requiring spontaneous speech output). All exercises included a minimum of 15 repetitions of each training task while incorporating sensory augmentation, such as cueing increased vocal effort and loudness, and sensory awareness by asking the children, “Did you feel your voice? Did you hear how you sounded?” Children practiced one homework session on treatment days (lasting 5–10 min) and two homework sessions on nontreatment days (lasting 10–15 min). Daily carryover exercises were specific assignments to use the new target voice with someone in the child's daily living environment—for example, “Say good morning to the bus driver using your ‘loud’ voice.” The impact of the carryover assignment was discussed in the next treatment session (e.g., “Did the bus driver understand you yesterday?”). Family members assisted the child in completing homework and carryover assignments. All participants and family members were encouraged to continue homework routines at the conclusion of treatment.
Participation of Typically Developing Peers
The typically developing peers participated in two recording sessions in 1 week's time, completing the same tasks as the participants with CP. These children did not participate in the laryngeal examination or the treatment phase of this study.
Analysis
Auditory–Perceptual Data (Listener Task)
A group of seven certified speech-language pathologists who had extensive experience in the areas of motor speech disorders and voice served as judges in a paired comparison listening task. Three repetitions of the sentences “Buy Bobby a puppy,” “The blue spot is on the key,” or “The potato stew is in the pot” from the final BASE, POST, and FUP recording sessions were included for speech samples. These final sessions were chosen to ensure that each child would have the greatest familiarity with the task across the study phases. Speech samples containing three repetitions of each of the sentences were constructed for BASE, POST, and FUP sessions. The order of presentation of speech samples was randomized across study phases (e.g., BASE vs. POST or FUP vs. BASE).
Listening task. Paired speech samples were presented to listeners via a computer and external speakers. They rated which sample they “preferred” for the following variables: (a) overall loudness, (b) loudness variability, (c) overall pitch, (d) pitch variability, (e) overall voice quality, and (f) articulatory precision. Listeners marked on a rating form which sample they “preferred,” Sample A, Sample B, or no preference. A listening CD was created for each participant. Practice speech samples, consisting of two randomly selected pairs for that child, were provided, during which the listener could adjust the volume control on the speakers to a loudness level that was comfortable. Once the volume control was set for a given participant, it did not change at any time during the listening task for that participant. Listeners were allowed to replay the samples as many times as they wanted prior to making their decision and were given the option to provide comments about why they chose one speech sample over another. The listening task took approximately 2 hr to complete. The number of times a speech sample was preferred from the BASE session, POST session, or FUP session or there was “no preference” (NP) was tabulated.
Statistical analysis. Auditory–perceptual data were analyzed using two chi-square tests on the categorical assignment of preference for each participant. The first chi-square test assessed the categorical assignment of preference for BASE versus POST versus NP. The second chi-square assessed the categorical assignment of preference for BASE versus FUP versus NP. Differences in the proportional distribution of preference for three preference categories were examined for each participant, based on an a priori probability model of equal likelihood of all three categories.
Acoustic Data
Data preparation and digitizing procedures. All acoustic data were reviewed, and problematic samples, such as clipped signals (approximately 10–15 samples across all participants and sessions) and faulty microphone signals (one recording session for two participants), were excluded. Data from the DAT tapes were digitized at 22.05 kHz with the commercial software program Praat (Boersma & Weenick, 2002). Each sample of a sustained vowel, high vowel, low vowel, or sentence repetition was saved in an individual .wav file. The calibration tone for each recording session was analyzed for dB SPL. The value of the calibration tone from Praat was subtracted from the recorded SLM value, creating a correction factor. The correction factor was applied to all dB SPL values produced by Praat, providing calibrated dB SPL at 4 in. across all participants and recording sessions.
Measurements. Vowel samples (longest, highest, lowest) from each session were displayed using Praat. Both the acoustic waveform and spectrogram, including intensity (dB SPL) and pitch (F0 in hertz) contours, were displayed for analysis. All acoustic measures were derived from standard Praat algorithms. The following measures were made for sustained vowel phonation: (a) maximum vowel duration (s) from the first to the last glottal pulse, (b) mean dB SPL (and SDs) from the first to the last glottal pulse, and (c) harmonics-to-noise ratio (HNR) selected from the middle 0.30-s segment of each vowel. For the highest and lowest vowel phonations, the acoustic waveform and pitch contours were inspected for any variations in voicing that interfered with the pitch tracking analysis, such as glottal fry. Aberrant segments were cut, and the F0 range was derived (maximum F0 – minimum F0) from the remaining pitch contour. Each digitized sentence repetition was filtered through a customized analysis program (Mathworks, code written by B. Story, 2002) that removed pauses and voiceless consonants. The acoustic waveforms, intensity contour (dB SPL), and pitch contour (Hz) of the filtered files were displayed using Praat. Pitch contours were inspected for any variations in voicing that interfered with the pitch tracking analysis, and aberrant segments were cut. The remaining voiced segment of the sentences was analyzed for mean (with SD) dB SPL and F0 range (maximum F0 – minimum F0) at each recording session.
Using the measures described above, we identified and graphed for visual analysis the following values from each recording session: (a) the duration of the single longest sustained vowel (s), (b) the maximum F0 range (Hz) from the single highest and lowest vowels, (c) the mean (and SD) dB SPL of the three longest vowels, (d) the mean (and SD) HNR of the three longest vowels, (e) mean (and SD) dB SPL of nine sentence repetitions, and (f) mean F0 range of nine sentence repetitions. The three longest duration vowels from each recording session were chosen for dB SPL and HNR of sustained phonation analysis to capture variability in trial-to-trial performance, versus only including the single “best” performance of the task (longest duration). Grand means (and SDs) also were calculated for each participant across BASE, POST, and FUP sessions. These data were used to compare performance of each participant with CP to mean (and SD) data of his or her yoked typically developing peer.
Visual analysis. Visual inspection was completed by three independent judges who did not have any contact with the children in the study. A total of 30 data graphs (six graphs per participant) of acoustic variables were visually analyzed for trend and overlapping data points (Barlow & Hersen, 1984). On the few occasions when there was disagreement between judges, the majority ruled (two of three).
Statistical analysis. Statistical analysis was applied according to the following rules: (a) if there was clear visual evidence of no treatment effect, defined as no variability in baseline data, no visual trends, and overlapping data points across all study phases, then no statistic was applied; (b) if there was clear visual evidence of a treatment effect, defined as a visual trend with no overlapping data points between study phases, statistics were used to confirm the effect; and (c) if there was unclear evidence of a treatment effect, defined as a visual trend with overlapping data points, or no visual trend with variable baseline data, statistics were applied to ascertain whether there was a possible treatment effect not evident through visual inspection of the graphed data.
We began our statistical analysis by checking for serial dependency in the data by running a lag-1 auto-correlation (Pearson) on neighboring data points in the baseline. If there was no significant auto-correlation, then we averaged data in each phase and conducted a one-way, repeated-measures analysis of variance (ANOVA). Least significant differences were used for post hoc comparisons. If baseline data were significantly correlated, then a split-middle binomial probabilities test was applied (Siegel, 1956). A lenient post hoc analysis and p value of <.05 for significance was chosen, allowing liberal tolerances for Type I errors, consistent with Phase 1 treatment research goals (Robey & Schultz, 1998). Effect size calculations were derived using a modified Cohen's d statistic (Busk & Serlin, 1992), as suggested by Beeson and Robey (2006)  for use with single-subject research designs. For comparison of participants with CP with their typically developing peers, a difference in mean beyond 2 SDs was considered significant.
Parent Rating Forms
Standard procedures for analysis of visual analog scales were used (Boeckstyns & Backer, 1989). The total distance of the line (15.2 cm) representing the continuum of presence or absence of a characteristic was measured. The distance of the slash on the line from right end of the continuum was measured and calculated into a percentage based on the total distance of the line (Fox & Ramig, 1997). This percentage represents the parents' perceived presence of a particular characteristic in the child with CP “most of the time.” Difference scores from BASE to POST and BASE to FUP were calculated. Given that there was only a single data point at BASE, POST, and FUP for parent ratings, statistical analyses were not applied.
Reliability
Auditory Perceptual Analysis
We determined intrarater reliability for the seven listeners by repeating 30% of the paired speech samples per participant in the listening task. Intrarater reliability across listeners ranged from 74% to 89%.
Acoustic Analysis
We calculated measurement reliability by having 20% of the data reanalyzed by a second measurer. Mean difference scores (MDs) and Pearson product–moment correlations (r) were calculated. Intermeasurer reliability scores were as follows: duration, MD = 0.005 s, r = .99; F0 range, MD = 28.5 Hz, r = .99; dB SPL of sustained phonation, MD = 0.03 dB SPL, r = .99; HNR of sustained phonation, MD = 0.01 dB SPL, r = .94; dB SPL of sentences, MD = 0.08 dB SPL, r = .99; F0 range of sentences, MD = 6.03 Hz, r = .90. These values represent good intermeasurer reliability.
Visual Analysis
We determined intrarater reliability for the three judges who visually examined data by randomly selecting 10 of the 30 graphs for repeated analysis. The intrarater reliability ranged from 98% to 100%. We determined interrater reliability by comparing agreements among the three raters. Interrater reliability was 94.7%.
Parent Ratings
We determined intrarater reliability of parent perceptual ratings by repeating a visual analog scale at one additional BASE, POST, or FUP recording. Intrarater reliability was available for all participants' parents except Participant 1 (P1). Mean difference scores (MDs) and Pearson product–moment correlations (r) were calculated. Intrarater reliability fell in the following ranges: MD = 7.00%–0.47% (0%–100% scale), r = .68–.90.
Results
Auditory–perceptual data and chi-square analyses are displayed in Table 2. The number of preference choices per BASE, POST, FUP, or NP (3 Sentence Pairs × 7 Listeners = 21 total choices per perceptual variable) and the accompanying statistic are listed. All acoustic data are displayed in Table 3. Effect size (ES) was commensurate with observed direction of change and statistical significance in all but one case (P1, dB SPL for sustained phonation). Judgments regarding magnitude of the ES were not made due to the Phase 1 nature of the study (Beeson & Robey, 2006). Difference scores across study phases of parent perceptual ratings (expressed in percentages) are displayed in Table 4. Positive and negative values reflect perceptions of improvement or deterioration, respectively.
Table 2. Summary analysis for auditory–perceptual data.
Summary analysis for auditory–perceptual data.×
Variable BASE–POST BASE–FUP
BASE POST NP p χ2 BASE FUP NP p χ2
P1
Overall loudness 2 14* 5 .004 11.14 9 2 10 .066 5.43
Loudness variability 2 11 8 .050 6.0 9 2 10 .066 5.43
Overall pitch 0 13* 8 .002 12.28 8 1 12* .012 8.86
Pitch variability 0 13* 8 .002 12.28 11* 1 9 .018 8.0
Overall voice quality 2 14* 5 .004 11.14 11 2 8 .050 6.0
Articulatory precision 1 19* 1 .000 30.86 8 4 9 .368 2.0
P2
Overall loudness 1 12* 1 .000 15.39 4 14* 3 .005 10.57
Loudness variability 2 11* 1 .002 13.0 8 13* 0 .002 12.27
Overall pitch 3 6 5 .607 1.0 3 10 8 .156 3.71
Pitch variability 2 10* 2 .010 9.14 4 13* 4 .021 7.71
Overall voice quality 1 9* 4 .030 7.0 3 14* 4 .005 10.57
Articulatory precision 0 4 10* .004 10.86 0* 11 10 .005 10.57
P3
Overall loudness 2 14* 5 .004 11.14 10 8 3 .156 3.71
Loudness variability 2 14* 5 .004 11.14 3 13* 5 .018 8.0
Overall pitch 0 8 13* .002 12.29 1 5 15* .001 14.86
Pitch variability 1 11* 9 .018 8.0 0* 11 10 .005 10.57
Overall voice quality 1 12* 8 .012 8.86 1 13* 7 .006 10.29
Articulatory precision 0 14* 7 .001 14.0 5 7 9 .565 1.14
P4
Overall loudness 1 19* 1 .000 30.86 0 16* 5 .000 19.14
Loudness variability 0 18* 3 .0001 26.57 0 17* 4 .000 22.57
Overall pitch 0 13* 8 .002 12.29 2 6 13* .012 8.86
Pitch variability 0 11* 10 .005 10.57 2 7 12* .028 7.14
Overall voice quality 0 20* 1 .0001 36.28 2 17* 2 .000 21.42
Articulatory precision 0 14* 7 .0009 14.0 1* 11 9 .018 8.0
P5
Overall loudness 1 3 17* .000 21.74 4 4 13* .021 7.71
Loudness variability 1 4 16* .000 18.0 5 5 11 .180 3.43
Overall pitch 1 3 17* .000 21.71 3 6 12* .050 6.0
Pitch variability 1 6 14* .002 12.29 4 6 11 .156 3.71
Overall voice quality 3 5 13* .018 8.00 3 8 10 .156 3.71
Articulatory precision 1 3 17* .000 21.74 6 3 12* .050 6.0
Note.For each perceptual variable, there were a total of 21 choices (3 Sentence Pairs × 7 Listeners) for each comparison BASE to POST and BASE to FUP (with the exception of P2 for POST). The values represent the number of listeners who preferred either a BASE, POST, FUP, or NP speech sample. Boldfaced and asterisked values indicate the preference (BASE, POST, FUP, or NP) that was statistically significant. P4 repeated only single words versus the entire sentence in this task. POST = posttreatment; FUP = follow-up; NP = no preference.
Note.For each perceptual variable, there were a total of 21 choices (3 Sentence Pairs × 7 Listeners) for each comparison BASE to POST and BASE to FUP (with the exception of P2 for POST). The values represent the number of listeners who preferred either a BASE, POST, FUP, or NP speech sample. Boldfaced and asterisked values indicate the preference (BASE, POST, FUP, or NP) that was statistically significant. P4 repeated only single words versus the entire sentence in this task. POST = posttreatment; FUP = follow-up; NP = no preference.×
Table 2. Summary analysis for auditory–perceptual data.
Summary analysis for auditory–perceptual data.×
Variable BASE–POST BASE–FUP
BASE POST NP p χ2 BASE FUP NP p χ2
P1
Overall loudness 2 14* 5 .004 11.14 9 2 10 .066 5.43
Loudness variability 2 11 8 .050 6.0 9 2 10 .066 5.43
Overall pitch 0 13* 8 .002 12.28 8 1 12* .012 8.86
Pitch variability 0 13* 8 .002 12.28 11* 1 9 .018 8.0
Overall voice quality 2 14* 5 .004 11.14 11 2 8 .050 6.0
Articulatory precision 1 19* 1 .000 30.86 8 4 9 .368 2.0
P2
Overall loudness 1 12* 1 .000 15.39 4 14* 3 .005 10.57
Loudness variability 2 11* 1 .002 13.0 8 13* 0 .002 12.27
Overall pitch 3 6 5 .607 1.0 3 10 8 .156 3.71
Pitch variability 2 10* 2 .010 9.14 4 13* 4 .021 7.71
Overall voice quality 1 9* 4 .030 7.0 3 14* 4 .005 10.57
Articulatory precision 0 4 10* .004 10.86 0* 11 10 .005 10.57
P3
Overall loudness 2 14* 5 .004 11.14 10 8 3 .156 3.71
Loudness variability 2 14* 5 .004 11.14 3 13* 5 .018 8.0
Overall pitch 0 8 13* .002 12.29 1 5 15* .001 14.86
Pitch variability 1 11* 9 .018 8.0 0* 11 10 .005 10.57
Overall voice quality 1 12* 8 .012 8.86 1 13* 7 .006 10.29
Articulatory precision 0 14* 7 .001 14.0 5 7 9 .565 1.14
P4
Overall loudness 1 19* 1 .000 30.86 0 16* 5 .000 19.14
Loudness variability 0 18* 3 .0001 26.57 0 17* 4 .000 22.57
Overall pitch 0 13* 8 .002 12.29 2 6 13* .012 8.86
Pitch variability 0 11* 10 .005 10.57 2 7 12* .028 7.14
Overall voice quality 0 20* 1 .0001 36.28 2 17* 2 .000 21.42
Articulatory precision 0 14* 7 .0009 14.0 1* 11 9 .018 8.0
P5
Overall loudness 1 3 17* .000 21.74 4 4 13* .021 7.71
Loudness variability 1 4 16* .000 18.0 5 5 11 .180 3.43
Overall pitch 1 3 17* .000 21.71 3 6 12* .050 6.0
Pitch variability 1 6 14* .002 12.29 4 6 11 .156 3.71
Overall voice quality 3 5 13* .018 8.00 3 8 10 .156 3.71
Articulatory precision 1 3 17* .000 21.74 6 3 12* .050 6.0
Note.For each perceptual variable, there were a total of 21 choices (3 Sentence Pairs × 7 Listeners) for each comparison BASE to POST and BASE to FUP (with the exception of P2 for POST). The values represent the number of listeners who preferred either a BASE, POST, FUP, or NP speech sample. Boldfaced and asterisked values indicate the preference (BASE, POST, FUP, or NP) that was statistically significant. P4 repeated only single words versus the entire sentence in this task. POST = posttreatment; FUP = follow-up; NP = no preference.
Note.For each perceptual variable, there were a total of 21 choices (3 Sentence Pairs × 7 Listeners) for each comparison BASE to POST and BASE to FUP (with the exception of P2 for POST). The values represent the number of listeners who preferred either a BASE, POST, FUP, or NP speech sample. Boldfaced and asterisked values indicate the preference (BASE, POST, FUP, or NP) that was statistically significant. P4 repeated only single words versus the entire sentence in this task. POST = posttreatment; FUP = follow-up; NP = no preference.×
×
Table 3. Summary analysis for acoustic data.
Summary analysis for acoustic data.×
Variable Grand means
BASE–POST
BASE–FUP
BASE POST FUP TP Visual STAT ES Visual STAT ES
P1
Max performance “ah” 2.4 3.5 4.4 16.1 p < .12a 1.1 p < .035a 2.0
Duration (s) (1.0) (1.0) (0.5) (2.8)
Max performance 200 436 301 884 p < .01a 5.6 p < .17a 2.4
F0 range (Hz) (42) (139) (45) (234)
Sustained phonation 87.4 87.4 87.4 96.5 p < .0001b 0.0 p < .0001b 0.0
dB SPL of 3 longest “ahs” (4.9) (2.9) (7.2) (1.3)
Sustained phonation 22.1 22.9 24.1 26.3 N/A 0.3 N/A 0.8
HNR of 3 longest “ahs” (2.3) (0.7) (0.8) (0.1)
Sentence repetition 75.0 76.4 76.0 74.9 N/A 0.9 N/A 0.6
dB SPL (1.6) (1.3) (0.74) (3.6)
Sentence repetition 62 76 66 96.1 N/A 2.0 N/A 0.6
F0 range (Hz) (7) (3) (16) (49)
P2
Max performance “ah” 1.8 5.7 7.0 11.4 p < .001a 6.5 p < .0001a 5.2
Duration (s) (0.6) (0.4) (1.4) (0.6)
Max performance 289 724 1097 2242 p < .0001b 2.0 p < .0001b 3.8
F0 range (Hz) (215) (147) (61)
Sustained phonation 86.3 94.6 99.4 95.3 p < .0001a 5.5 p < .0001a 8.7
dB SPL of 3 longest “ahs” (1.5) (1.1) (1.0) (2.3)
Sustained phonation 22.0 22.0 24.0 27.9 p < .87a 0.0 p < .451a 0.9
HNR of 3 longest “ahs” (2.3) (2.8) (1.3) (1.6)
Sentence repetition 73.0 82.0 83.5 78.6 p < .005a 4.7 p < .002a 5.5
dB SPL (1.9) (0.4) (4.4) (0.4)
Sentence repetition 109 131 225 180 p < .23a 1.4 p < .003a 7.3
F0 range (Hz) (16) (23) (26) (29)
P3
Max performance “ah” 5.3 6.8 13.4 15.7 p < .05a 1.9 p < .001a 10.1
Duration (s) (0.8) (0.6) (1.0)
Max performance 796 633 1005 2853 p < .14a −1.3 p < .07a 1.6
F0 range (Hz) (127) (112) (48)
Sustained phonation 82.4 84.2 87.2 93.9 N/A 0.7 N/A 1.8
dB SPL of 3 longest “ahs” (2.7) (2.8) (2.6)
Sustained phonation 19.2 21.7 23.3 26.4 N/A 0.5 N/A 0.8
HNR of 3 longest “ahs” (4.9) (0.5) (4.0)
Sentence repetition 80.4 79.3 82.9 74.4 p < .861a −0.4 p < .626a 0.4
dB SPL (2.9) (2.9) (3.7)
Sentence repetition 118 128 134 107 N/A 0.6 N/A 0.9
F0 Range (Hz) (18) (32) (38)
P4
Max performance “ah” 1.0 1.2 1.5 16.9 N/A 0.3 N/A 0.7
Duration (s) (0.7) (0.2) (0.4) (0.1)
Max performance 137 211 185 1638 p < .0001b 2.2 p < .0001b 1.4
F0 range (Hz) (34) (21) (18) (1099)
Sustained phonation 83.1 87.5 89.4 94.3 N/A 0.4 N/A 0.6
dB SPL of 3 longest “ahs” (10.1) (2.5) (1.4) (0.5)
Sustained phonation 15.6 19.3 24.5 26.8 p < .17a 0.8 p < .03a 2.0
HNR of 3 longest “ahs” (4.4) (2.0) (0.7) (0.5)
Sentence repetition 70.4 75.0 76.8 75.7 p < .001b 1.1 p < .001b 1.5
dB SPL (4.4) (0.7) (0.6)
Sentence repetition 34 42 52 118 N/A 0.4 N/A 1.0
F0 range (Hz) (18) (9) (6)
P5
Max performance “ah” 6.7 7.4 7.3 15.8 N/A 0.5 N/A 0.4
Duration (s) (1.4) (1.3) (0.8) (5.3)
Max performance 860 519 719 1066 p < .02a −2.3 p < .24a −0.1
F0 range (Hz) (146) (81) (69) (110)
Sustained phonation 95.1 91.2 95.3 99.7 p < .20a −2.8 p < .95a 0.1
dB SPL of 3 longest “ahs” (1.4) (5.04) (4.2) (3.6)
Sustained phonation 22.6 22.9 21.7 28.9 N/A 0.1 N/A −0.2
HNR of 3 longest “ahs” (4.7) (0.5) (2.47) (0.2)
Sentence repetition 78.9 78.5 78.4 86.9 N/A −0.2 N/A −0.2
dB SPL (2.4) (1.9) (2.5) (0.1)
Sentence repetition 132 106 96 165 N/A −0.7 N/A −0.9
F0 range (Hz) (38) (8) (141) (0.7)
Note.Mean data across BASE, POST, FUP, and TP are presented with SDs in parentheses. Effect sizes were calculated using a Cohen's (1988)  d statistic modified by Busk and Serlin (1992) . Direction of arrows and triangles reflects direction of change (“up” indicating improvements, “down” indicating worsening). TP = typically developing peer; Visual = summary of the visual trend analysis; STAT = results of the statistical analysis, if applied; ▴ or ▾ = visual trends with nonoverlapping data points; ↑ or ↓ = visual trends with overlapping data points; — = no visual trend in the data, including instances of variable baseline data; HNR = harmonics-to-noise ratio; N/A = statistics not applied.
Note.Mean data across BASE, POST, FUP, and TP are presented with SDs in parentheses. Effect sizes were calculated using a Cohen's (1988)  d statistic modified by Busk and Serlin (1992) . Direction of arrows and triangles reflects direction of change (“up” indicating improvements, “down” indicating worsening). TP = typically developing peer; Visual = summary of the visual trend analysis; STAT = results of the statistical analysis, if applied; ▴ or ▾ = visual trends with nonoverlapping data points; ↑ or ↓ = visual trends with overlapping data points; — = no visual trend in the data, including instances of variable baseline data; HNR = harmonics-to-noise ratio; N/A = statistics not applied.×
a p value derived through analysis of variance.
p value derived through analysis of variance.×
b p value derived through split-middle binomial probability test.
p value derived through split-middle binomial probability test.×
Table 3. Summary analysis for acoustic data.
Summary analysis for acoustic data.×
Variable Grand means
BASE–POST
BASE–FUP
BASE POST FUP TP Visual STAT ES Visual STAT ES
P1
Max performance “ah” 2.4 3.5 4.4 16.1 p < .12a 1.1 p < .035a 2.0
Duration (s) (1.0) (1.0) (0.5) (2.8)
Max performance 200 436 301 884 p < .01a 5.6 p < .17a 2.4
F0 range (Hz) (42) (139) (45) (234)
Sustained phonation 87.4 87.4 87.4 96.5 p < .0001b 0.0 p < .0001b 0.0
dB SPL of 3 longest “ahs” (4.9) (2.9) (7.2) (1.3)
Sustained phonation 22.1 22.9 24.1 26.3 N/A 0.3 N/A 0.8
HNR of 3 longest “ahs” (2.3) (0.7) (0.8) (0.1)
Sentence repetition 75.0 76.4 76.0 74.9 N/A 0.9 N/A 0.6
dB SPL (1.6) (1.3) (0.74) (3.6)
Sentence repetition 62 76 66 96.1 N/A 2.0 N/A 0.6
F0 range (Hz) (7) (3) (16) (49)
P2
Max performance “ah” 1.8 5.7 7.0 11.4 p < .001a 6.5 p < .0001a 5.2
Duration (s) (0.6) (0.4) (1.4) (0.6)
Max performance 289 724 1097 2242 p < .0001b 2.0 p < .0001b 3.8
F0 range (Hz) (215) (147) (61)
Sustained phonation 86.3 94.6 99.4 95.3 p < .0001a 5.5 p < .0001a 8.7
dB SPL of 3 longest “ahs” (1.5) (1.1) (1.0) (2.3)
Sustained phonation 22.0 22.0 24.0 27.9 p < .87a 0.0 p < .451a 0.9
HNR of 3 longest “ahs” (2.3) (2.8) (1.3) (1.6)
Sentence repetition 73.0 82.0 83.5 78.6 p < .005a 4.7 p < .002a 5.5
dB SPL (1.9) (0.4) (4.4) (0.4)
Sentence repetition 109 131 225 180 p < .23a 1.4 p < .003a 7.3
F0 range (Hz) (16) (23) (26) (29)
P3
Max performance “ah” 5.3 6.8 13.4 15.7 p < .05a 1.9 p < .001a 10.1
Duration (s) (0.8) (0.6) (1.0)
Max performance 796 633 1005 2853 p < .14a −1.3 p < .07a 1.6
F0 range (Hz) (127) (112) (48)
Sustained phonation 82.4 84.2 87.2 93.9 N/A 0.7 N/A 1.8
dB SPL of 3 longest “ahs” (2.7) (2.8) (2.6)
Sustained phonation 19.2 21.7 23.3 26.4 N/A 0.5 N/A 0.8
HNR of 3 longest “ahs” (4.9) (0.5) (4.0)
Sentence repetition 80.4 79.3 82.9 74.4 p < .861a −0.4 p < .626a 0.4
dB SPL (2.9) (2.9) (3.7)
Sentence repetition 118 128 134 107 N/A 0.6 N/A 0.9
F0 Range (Hz) (18) (32) (38)
P4
Max performance “ah” 1.0 1.2 1.5 16.9 N/A 0.3 N/A 0.7
Duration (s) (0.7) (0.2) (0.4) (0.1)
Max performance 137 211 185 1638 p < .0001b 2.2 p < .0001b 1.4
F0 range (Hz) (34) (21) (18) (1099)
Sustained phonation 83.1 87.5 89.4 94.3 N/A 0.4 N/A 0.6
dB SPL of 3 longest “ahs” (10.1) (2.5) (1.4) (0.5)
Sustained phonation 15.6 19.3 24.5 26.8 p < .17a 0.8 p < .03a 2.0
HNR of 3 longest “ahs” (4.4) (2.0) (0.7) (0.5)
Sentence repetition 70.4 75.0 76.8 75.7 p < .001b 1.1 p < .001b 1.5
dB SPL (4.4) (0.7) (0.6)
Sentence repetition 34 42 52 118 N/A 0.4 N/A 1.0
F0 range (Hz) (18) (9) (6)
P5
Max performance “ah” 6.7 7.4 7.3 15.8 N/A 0.5 N/A 0.4
Duration (s) (1.4) (1.3) (0.8) (5.3)
Max performance 860 519 719 1066 p < .02a −2.3 p < .24a −0.1
F0 range (Hz) (146) (81) (69) (110)
Sustained phonation 95.1 91.2 95.3 99.7 p < .20a −2.8 p < .95a 0.1
dB SPL of 3 longest “ahs” (1.4) (5.04) (4.2) (3.6)
Sustained phonation 22.6 22.9 21.7 28.9 N/A 0.1 N/A −0.2
HNR of 3 longest “ahs” (4.7) (0.5) (2.47) (0.2)
Sentence repetition 78.9 78.5 78.4 86.9 N/A −0.2 N/A −0.2
dB SPL (2.4) (1.9) (2.5) (0.1)
Sentence repetition 132 106 96 165 N/A −0.7 N/A −0.9
F0 range (Hz) (38) (8) (141) (0.7)
Note.Mean data across BASE, POST, FUP, and TP are presented with SDs in parentheses. Effect sizes were calculated using a Cohen's (1988)  d statistic modified by Busk and Serlin (1992) . Direction of arrows and triangles reflects direction of change (“up” indicating improvements, “down” indicating worsening). TP = typically developing peer; Visual = summary of the visual trend analysis; STAT = results of the statistical analysis, if applied; ▴ or ▾ = visual trends with nonoverlapping data points; ↑ or ↓ = visual trends with overlapping data points; — = no visual trend in the data, including instances of variable baseline data; HNR = harmonics-to-noise ratio; N/A = statistics not applied.
Note.Mean data across BASE, POST, FUP, and TP are presented with SDs in parentheses. Effect sizes were calculated using a Cohen's (1988)  d statistic modified by Busk and Serlin (1992) . Direction of arrows and triangles reflects direction of change (“up” indicating improvements, “down” indicating worsening). TP = typically developing peer; Visual = summary of the visual trend analysis; STAT = results of the statistical analysis, if applied; ▴ or ▾ = visual trends with nonoverlapping data points; ↑ or ↓ = visual trends with overlapping data points; — = no visual trend in the data, including instances of variable baseline data; HNR = harmonics-to-noise ratio; N/A = statistics not applied.×
a p value derived through analysis of variance.
p value derived through analysis of variance.×
b p value derived through split-middle binomial probability test.
p value derived through split-middle binomial probability test.×
×
Table 4. Parents' perceptual ratings of their child's voice, speech, and communication “most of the time.”
Parents' perceptual ratings of their child's voice, speech, and communication “most of the time.”×
Perceptual characteristic Difference scores in parent perceptual ratings
P1
P2
P3
P4
P5
B − P B − F B − P B − F B − P B − F B − P B − F B − P B − F
Always loud enough 44 5 39 40 33 23 32 8
Never nasal voice 8 −2 11 13 4 1 −18 14
Never hoarse, scratchy voice 20 22 1 2 6 2 −31 26
Never monotone 5 −7 32 38 3 15 6 −1
Never breathy voice 31 2 39 39 22 12 1 6
Never strained voice 17 −19 7 5 28 19 −2 −2
Always speaks so others can understand 18 −10 20 24 13 0 −9 −30
Always talks when playing with kids 18 71 3 5 17 −2 0 −11
Always starts talking with other kids 23 72 7 5 14 2 −22 −10
Never frustrated when talking 23 10 −3 −5 26 13 25 −2
Note.B − P is the difference score in percentage rating from BASE to POST; B − F is the difference score in percentage rating from BASE to FUP. Positive values reflect improved perceptions; negative values reflect worsening perceptions.
Note.B − P is the difference score in percentage rating from BASE to POST; B − F is the difference score in percentage rating from BASE to FUP. Positive values reflect improved perceptions; negative values reflect worsening perceptions.×
Table 4. Parents' perceptual ratings of their child's voice, speech, and communication “most of the time.”
Parents' perceptual ratings of their child's voice, speech, and communication “most of the time.”×
Perceptual characteristic Difference scores in parent perceptual ratings
P1
P2
P3
P4
P5
B − P B − F B − P B − F B − P B − F B − P B − F B − P B − F
Always loud enough 44 5 39 40 33 23 32 8
Never nasal voice 8 −2 11 13 4 1 −18 14
Never hoarse, scratchy voice 20 22 1 2 6 2 −31 26
Never monotone 5 −7 32 38 3 15 6 −1
Never breathy voice 31 2 39 39 22 12 1 6
Never strained voice 17 −19 7 5 28 19 −2 −2
Always speaks so others can understand 18 −10 20 24 13 0 −9 −30
Always talks when playing with kids 18 71 3 5 17 −2 0 −11
Always starts talking with other kids 23 72 7 5 14 2 −22 −10
Never frustrated when talking 23 10 −3 −5 26 13 25 −2
Note.B − P is the difference score in percentage rating from BASE to POST; B − F is the difference score in percentage rating from BASE to FUP. Positive values reflect improved perceptions; negative values reflect worsening perceptions.
Note.B − P is the difference score in percentage rating from BASE to POST; B − F is the difference score in percentage rating from BASE to FUP. Positive values reflect improved perceptions; negative values reflect worsening perceptions.×
×
Data for P1
Listener Ratings
Chi-square analysis revealed statistically significant preferences for the POST over BASE samples across all perceptual variables except loudness variability. These preferences were not maintained at FUP. Listener comments for preference of POST samples included “louder,” “more variable,” “pitch more stable,” “natural,” “less strain,” “decreased nasal emissions,” “more crisp,” and “less effort.” Comments for preference of BASE samples included “more consistent loudness,” “louder,” and “less gurgle.”
Acoustic Analysis
The measures for which a visual treatment effect was observable and for which a statistically significant difference was found included maximum F0 range from BASE to POST and maximum duration “ah” from BASE to FUP. P1 was 2 SDs below the mean values of his matched typically developing peer at BASE, POST, and FUP for all variables except dB SPL and F0 range of sentence repetition at all phases.
Parent Ratings
Perceptual variables with the greatest percentage increase from BASE to POST included “always loud enough” (44%) and “never breathy voice” (31%). These percentage increases from BASE to FUP were not maintained at 5% and 2%, respectively.
Data for P2
Listener Ratings
Chi-square analysis revealed statistically significant preferences for both POST over BASE and FUP over BASE samples for overall loudness, loudness variability, pitch variability, and overall voice quality. Listener comments for preference of POST or FUP samples included “louder,” “more variable,” “not strained,” “less monotone,” “more precise,” and “less hoarse.” Comments when a BASE sample was preferred over FUP included “not yelling,” which referred to her FUP repetition of “Buy Bobby a puppy.”
Acoustic Analysis
The measures that had a visual treatment effect and also were statistically significant included maximum duration “ah,” maximum F0 range, dB SPL of sustained phonation, dB SPL of sentence repetition from BASE to POST and BASE to FUP, and F0 range for sentence repetition from BASE to FUP. P2 was 2 SDs below the mean value of her matched typically developing peer for all variables at BASE, POST, and FUP except dB SPL of sustained phonation, and F0 range of sentence repetition at POST and FUP. She was 2 SDs above the mean value for dB SPL of sentence repetition.
Parent Ratings
Perceptual variables with the greatest percentage increase from BASE to POST included “always loud enough” (39%) and “never breathy voice” (39%). These percentage increases from BASE to FUP were maintained at 40% and 39%, respectively.
Data for P3
Listener Ratings
Chi-square analysis revealed statistically significant preferences for the POST over BASE samples for all variables except overall pitch. Preference for loudness variability and overall voice quality were maintained at FUP. Listener comments for preference of POST or FUP samples included “more precise,” “louder,” “consistent loudness,” “less breathy,” “less strain and strangle,” and “clearer voice quality.”
Acoustic Analysis
The measure that had a visual treatment effect, which also was statistically significant, was maximum sustained “ah” from BASE to FUP. P3 was 2 SDs below the mean value of his matched typically developing peer for all variables at BASE, POST, and FUP, except for HNR of sustained phonation and dB SPL and F0 range of sentence repetition at all study phases.
Parent Ratings
Perceptual variables with the greatest percentage increase from BASE to POST included “always loud enough” (33%) and “never strained voice” (28%). These percentage increases from BASE to FUP were somewhat maintained at 23% and 19%, respectively.
Data for P4
P4 was unable to repeat entire sentences; therefore, he repeated the last word of each sentence (“puppy,” “pot,” “key”) during the sentence repetition task. There are no data for sentence repetition at BASE 2 due to P4's unwillingness to perform the task and at FUP 2 due to microphone failure.
Listener Ratings
Chi-square analysis revealed statistically significant preferences for the POST over BASE single-word repetition samples across all six perceptual variables rated. Preference for overall loudness, loudness variability, and overall voice quality were maintained at FUP. Listener comments for preference of POST or FUP samples included “louder,” “more variable,” “less breathy,” “less pressed,” “easier for child to produce,” “more precise,” and “more natural pitch.”
Acoustic Analysis
The measures that had a visual treatment effect and also were statistically significant included maximum F0 range from BASE to POST and maximum F0 range, HNR of sustained phonation, and dB SPL of his single-word repetition from BASE to FUP. P4 was two SDs below the mean value of his matched typically developing peer for all variables at BASE, POST, and FUP, except for maximum F0 range at all phases and dB SPL of sentences at POST and FUP.
Parent Perceptual Ratings
The perceptual variable with the greatest percentage increase from BASE to POST was for “always loud enough” (33%). The second largest percentage change was in a negative direction reflecting an increase in the perception of a “hoarse, scratchy voice” (−31%). Data for FUP measures from the same parent who completed the BASE and POST ratings were not available.
Data for P5
P5 was an untreated comparison participant in this study. Therefore, the study phases of POST and FUP were actually additional BASE recordings following 1 month and an additional 6 weeks of no treatment.
Listener Ratings
Chi-square analysis revealed statistically significant preferences for the NP category for all variables rated from BASE to POST and for overall loudness, overall pitch, and articulatory precision at the FUP session.
Acoustic Analysis
The measure that had a visual treatment effect and also was statistically significant was a decreasing performance for maximum F0 range from BASE to POST. P5 was 2 SDs below the mean value of her matched typically developing peer for all variables at BASE, POST, and FUP except maximum duration at all phases, maximum F0 range at BASE, and dB SPL of sustained phonation at BASE and FUP.
Parent Ratings
The perceptual variable with the greatest percentage increase from BASE to POST was for “never hoarse, scratchy voice” (26%). The next largest percentage change was a decrease (worsening) for the perception of “always speaks so others can understand” (−30%). Data for FUP measures from the same parent who completed the BASE and POST ratings were not available.
Discussion
This Phase 1 treatment study examined the effects of an intensive voice treatment in children with spastic CP and dysarthria. A nonconcurrent single-subject multiple baseline design with replication across participants was used. Listeners preferred POST speech samples for loudness, pitch variability, and voice quality over BASE speech samples in all four treated participants. Treated participants made a significant gain in at least one acoustic measure during maximum performance tasks; improvements were not as frequently observed for speech. All parents rated an improved percentage for “always loud enough” from BASE to POST. Maintenance of these perceptual and acoustic changes at FUP varied across participants and are detailed below. The untreated participant did not make improvements over the course of the study. The implications of these findings and directions for future research are discussed below.
Listener Preferences
Listeners preferred POST over BASE speech samples from the sentence repetition task for most of the perceptual variables rated, including five of six for P1, four of six for P2, five of six for P3, and six of six for single-word repetitions for P4. These listener ratings support an immediate therapeutic effect of the intervention. However, these findings should be interpreted with caution for a number of reasons. First, a lenient p value, which is consistent with Phase 1 treatment research goals, increased the potential for Type 1 error (treatment effect identified when none exists). Second, perceptual variables rated in this study were not specifically defined for the listeners. Although loudness, pitch, voice quality, and articulatory precision are standard perceptions, listeners may have interpreted these variables differently. Third, the intrarater reliability for some of the listeners was borderline acceptable. Finally, the model for sentence repetition was provided by verbal output from data collectors. Although these data collectors were well trained on presentation style of the sentences, we cannot eliminate the possibility that differences in models may have affected the participants' speech. Future research using prerecorded samples, perhaps with animated characters to engage children (e.g., Test of Children's Speech by Hodge, Daniels, & Gotzke, 2006) would standardize this task presentation.
Acoustic Measures
Overall there were minimal changes in acoustic measures across study phases, with the exception of P2. In addition, most participants with CP were still 2 SDs below the mean performance of their typically developing peers for maximum performance tasks after treatment. These findings are consistent with those of Wit, Maassen, Gabreels, and Thoonen (1993), who reported that children with spastic CP were significantly reduced in their performance envelope compared with typically developing peers. These findings also are different from the pattern of results found in adults with PD who nearly always have large and significant changes in maximum performance tasks, which are trained targets in LSVT LOUD (Sapir, Ramig, & Fox, 2011). This was most likely related to the different etiology of the dysarthria in PD versus CP. In PD, the soft voice is often due to deficits in scaling amplitude of motor output and sensory perception of normal loudness (Sapir et al., 2011). Targeting vocal loudness in people with PD may cue or access a relatively intact motor system that is capable of scaling up output to produce normal vocal loudness. In CP, the soft voice is related to generalized weakness of respiratory and laryngeal systems, coupled with a lack of coordination between the respiratory and laryngeal subsystems (Ansel & Kent, 1992; Workinger & Kent, 1991). Thus, unlike in PD, there may be inherent neuromuscular limitations in CP that impact gains on tasks targeting the maximum performance envelope.
The acoustic variables measured for sentence repetition (mean vocal SPL and F0 range) may not have been adequate to capture what the listeners perceived in speech, when they preferred POST speech samples. Selecting different or additional acoustic measures in future studies may better capture potential changes in vocal motor functioning that underlie the listener-perceived changes. For example, including the entire speech envelope in vocal SPL analysis for sentences versus a focus on the voiced segments may capture the “whispered” elements of some participants' speech at the end of sentences. Although the acoustic measures did not document significant changes for most participants, written comments from listeners often indicated that children spoke with “less effort,” “less strain and strangle,” or “less of a struggle.” These perceptions of decreased effort and strain are not reflected in measures of vocal SPL or F0 range and may have been the basis of listener preference of POST samples.
Using multiple strategies to detect change in single-subject designs may provide the best interpretation of data. For example, P1 revealed no visual trend, no mean differences, and no effect size for dB SPL of sustained phonation, yet the split-middle technique revealed a statistically significant difference. In this case, the statistical detection of a true change is suspect. Conversely, P2 exhibited a visual trend, a statistically significant difference, and a relatively large effect size for POST and FUP duration of sustained phonation. In this case, a true change is likely. The interpretation of effect size in this study is limited. The ability to interpret effect sizes in single-subject designs requires averaging them across studies in order to establish meaningful effect size magnitudes for specific variables of interest for a given treatment approach (Beeson & Robey, 2006). Including effect size calculations in the current study will contribute to interpretation of outcomes from future studies.
Changes in Parent Ratings
Qualitative information from parent ratings identified improvement on some perceptual variables, which may indicate a possible impact in the participant's daily living, outside of the laboratory setting. Parent ratings corroborated many of the listener perceptions of improvement immediately posttreatment. Although the parent ratings must be interpreted with caution, given the lack of replication, moderate intrarater reliability, and descriptive level of analysis, they are a step in the direction of assessing external validity of the findings. Future work should continue to address the perceived impact of treatment on family, friends, and teachers in the environment.
Did Treatment Effects Last?
Maintenance of listener preferences at FUP varied across participants. Listeners did not perceive P1 to have maintained any of the improvements in perceptual characteristics from BASE to FUP, but listeners perceived P2 to have maintained all of the improvements from BASE to FUP, P3 to have maintained two of the five improvements from BASE to FUP, and P4 to have maintained three of the six improvements from BASE to FUP. Perceptions of improvement that were maintained included those most closely related to the treatment target of voice (e.g., overall loudness, loudness variability, and overall voice quality). All acoustics measures showed maintenance or improvement of skill from BASE to FUP with the exception of F0 range for P1. Parent perceptual ratings at FUP were not maintained at POST levels for P1, but they were maintained for P2 and somewhat maintained for P3. FUP data were not available from the parents of P4.
The maintenance of treatment effects may have depended on multiple factors, such as acceptance of the treatment techniques and family support. Although we did not systematically log home practice in the 6-week interval between POST and FUP, parents reported on their child's progress. P2's parent indicated that she frequently reminded herself to use her loud/strong voice and she did so regularly in daily communication. P3's mother reported that if she could not understand her son, cueing him to repeat with his “strong voice” was a helpful strategy. P4 had four older siblings who constantly cued him to use his “big voice.” For P1, changes in speech were not maintained according to listener and parent ratings. The parent reported that P1 was unwilling to practice on his own or with family members.
General Comments on Treatment Mode and Target
The intensive treatment protocol consistent with select principles of motor learning and activity-dependent neuroplasticity was well tolerated by all participants, with 100% compliance during the treatment phase. These findings are similar to those of Schindl et al. (2000)  for an intensive gait-training program and Pennington et al. (2010)  for intensive speech therapy for children with CP. According to parent report, physical fatigue occurred in most participants at the start of treatment; however, over time they reported that fatigue diminished. P1's parent even reported in later treatment sessions that he was “energized” and performed better on other tasks, such as physical therapy, when they occurred on the same day. Repeated active-practice trials in therapy were also well tolerated by participants with CP. Most of the treatment sessions were completed without breaks for rest.
The treatment target of vocal loudness was highly salient to the participants. At BASE, all parents reported concerns about their child's vocal loudness, citing “soft speech,” “breathy, quiet voice,” “maintaining loudness at end of sentences,” and “whispered voice.” At the same time, the speech-language pathologists reported that some of these children also had occurrences of “harsh voice quality” and “strained voice quality.” We speculate that the poor voice quality that occurred prior to treatment may have been the result of compensatory strategies to overcome generalized weakness of respiratory and laryngeal musculature (Ansel & Kent, 1992). With treatment, the need for compensatory behaviors may have been diminished at POST and replaced with improved vocal strategies as indicated by listener comments of “less strain [or pressed or strangled]” for all four treated participants. This is similar to findings in individuals with PD after treatment with LSVT LOUD (Countryman, Hicks, Ramig, & Smith, 1997). To confirm these speculations, further study is needed in children with CP and dysarthria. Severity of dysarthria also may play a role in treatment success. The child with CP who demonstrated the greatest improvements across all acoustic measures in this study (P2) had the mildest rating of dysarthria. P3 differed slightly from the other participants in that he was described as having spastic–ataxic dysarthria characterized by variable loudness. For this participant, listeners preferred POST and FUP speech samples on the measure of loudness variability, which is consistent with reported improved control over variable loudness post-LSVT in an adult with ataxic dysarthria (Sapir et al., 2003). For P4, the parents rated increased hoarseness at POST. This may be explained by the fact that, after therapy, P4 was voicing versus whispering, which may have made parents more aware of vocal quality. Increased hoarseness was not reported by listener perceptions of improved voice quality on single-word repetitions at POST and FUP or with reported HNR values.
Study Limitations and Future Directions
The single-subject design used for this study precludes generalization of these results to the population of children with spastic CP. The liberal tolerance of Type I errors may have overestimated some of the treatment outcomes. Adding a spontaneous speech task with a peer or parent interaction in a naturalistic environment would have been desirable. The inclusion of systematic monitoring of homework practice sessions would have been helpful for the interpretation of skills maintenance. Furthermore, there is a need for including ratings of speech intelligibility at a single-word and connected speech level (Pennington et al., 2010).
Future studies may investigate additional acoustic parameters of voice and speech. Examining potential physiological changes that may accompany treatment will provide insight into the mechanism of change. In addition, examination of alternative treatment targets (e.g., oromotor exercises or articulation) administered in a parallel mode and intensity will help delineate key elements of treatment success. Future studies are also required to determine duration of treatment effects (e.g., more than 6 weeks) and to delineate the most effective dosage. Finally, studies that engage a larger number of children with spastic CP are required to determine generalizability of treatment outcomes for this population.
Summary
Improving speech in children with CP is challenging. Many of these children have a range of medical problems, multiple speech mechanism disorders, and cognitive deficits, all of which may limit the magnitude and long-term effects of treatment outcomes. This Phase 1 treatment study (Robey & Schultz, 1998) examined a standardized treatment approach (LSVT LOUD) in children with spastic CP and dysarthria. Findings provide some preliminary support for intensive voice treatment to improve select aspects of vocal functioning in the children with spastic CP and dysarthria who participated in this study. Future Phase 2 treatment research studies are warranted.
Acknowledgments
This work was supported, in part, by National Multipurpose Research and Training Center Grant DC-01409 from the National Institute of Deafness and Other Communication Disorders and by the Final Project Fund from the Graduate College at the University of Arizona. This article is based on a doctoral dissertation completed by Cynthia Marie Fox at the University of Arizona under the direction of Carol Ann Boliek and Jeannette Hoit. We thank Jeannette Hoit, Brad Story, Leslie Tolbert, Becky Farley, and Lorraine Ramig for their expert advice. Special thanks go to the children and families who participated in this study.
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Table 1. Participant characteristics.
Participant characteristics.×
Descriptor Participant
P1 P2 P3 P4 P5
Age (years;months) 7;10 5;10 6;1 7;7 6;7
Gender Male Female Male Male Female
Diagnosis Spastic quadriparesis due to CP; secondary seizure disorder Spastic quadriparesis due to CP Spastic quadriparesis secondary to CP Spastic quadriparesis secondary to CP Spastic quadriparesis secondary to CP
Parent-reported speech andvoice concerns “Breathy, quiet voice with weak breath support,” did not have confidence with speaking (e.g., “intimidated by other kids”) Weak breath control, soft speech, “choppy speech” (i.e., took a lot of breaths to finish a sentence) Improving breath control, improving clarity of speech, maintaining loudness and clarity at end of sentences Breath control; quiet, “whispered” voice; short utterances “Take a full tidal breath,” not always having enough breath, stopping in the middle of sentences to get a breath, breathing coordination
Observed speech and voice signs (2 SLPs) Reduced loudness, monotone, intermittent hypernasality, intermittent harshness, imprecise consonants, variable slow rate (task dependent), prosodic abnormalities Variable loudness, inconsistent breathy-harsh voice quality, inconsistent slow rate, whispered at end of sentences, mild articulatory imprecision Variable loudness, irregular articulatory breakdowns, variable rate, strained voice quality with occasional voice stoppages, intermittent glottal fry Minimal voicing, reduced loudness to aphonic, monotone, imprecise articulation, spoke only 1–2 word phrases Variable loudness; variable pitch; inconsistent strained voice quality, especially at end of sentences; mild, imprecise articulation
Dysarthria type Spastic Spastic Mixed spastic/ataxic Spastic Spastic
Overall dysarthria severity Moderate Mild–moderate Moderate Marked Moderate
Study condition Condition A 4 BASE/2 weeks Condition C 5 BASE/5 weeks Condition B 5 BASE/3 weeks Condition A 4 BASE/3 weeks Condition D 4 BASE/3 weeks
Age (years;months), gender-matched control 7;6 Male 6;2 Female 6;1 Male 7;1 Male 7;0 Female
Note.P1 (P2, etc.) = Participant 1 (2, etc.); CP = cerebral palsy; SLP = speech-language pathologist; BASE = baseline.
Note.P1 (P2, etc.) = Participant 1 (2, etc.); CP = cerebral palsy; SLP = speech-language pathologist; BASE = baseline.×
Table 1. Participant characteristics.
Participant characteristics.×
Descriptor Participant
P1 P2 P3 P4 P5
Age (years;months) 7;10 5;10 6;1 7;7 6;7
Gender Male Female Male Male Female
Diagnosis Spastic quadriparesis due to CP; secondary seizure disorder Spastic quadriparesis due to CP Spastic quadriparesis secondary to CP Spastic quadriparesis secondary to CP Spastic quadriparesis secondary to CP
Parent-reported speech andvoice concerns “Breathy, quiet voice with weak breath support,” did not have confidence with speaking (e.g., “intimidated by other kids”) Weak breath control, soft speech, “choppy speech” (i.e., took a lot of breaths to finish a sentence) Improving breath control, improving clarity of speech, maintaining loudness and clarity at end of sentences Breath control; quiet, “whispered” voice; short utterances “Take a full tidal breath,” not always having enough breath, stopping in the middle of sentences to get a breath, breathing coordination
Observed speech and voice signs (2 SLPs) Reduced loudness, monotone, intermittent hypernasality, intermittent harshness, imprecise consonants, variable slow rate (task dependent), prosodic abnormalities Variable loudness, inconsistent breathy-harsh voice quality, inconsistent slow rate, whispered at end of sentences, mild articulatory imprecision Variable loudness, irregular articulatory breakdowns, variable rate, strained voice quality with occasional voice stoppages, intermittent glottal fry Minimal voicing, reduced loudness to aphonic, monotone, imprecise articulation, spoke only 1–2 word phrases Variable loudness; variable pitch; inconsistent strained voice quality, especially at end of sentences; mild, imprecise articulation
Dysarthria type Spastic Spastic Mixed spastic/ataxic Spastic Spastic
Overall dysarthria severity Moderate Mild–moderate Moderate Marked Moderate
Study condition Condition A 4 BASE/2 weeks Condition C 5 BASE/5 weeks Condition B 5 BASE/3 weeks Condition A 4 BASE/3 weeks Condition D 4 BASE/3 weeks
Age (years;months), gender-matched control 7;6 Male 6;2 Female 6;1 Male 7;1 Male 7;0 Female
Note.P1 (P2, etc.) = Participant 1 (2, etc.); CP = cerebral palsy; SLP = speech-language pathologist; BASE = baseline.
Note.P1 (P2, etc.) = Participant 1 (2, etc.); CP = cerebral palsy; SLP = speech-language pathologist; BASE = baseline.×
×
Table 2. Summary analysis for auditory–perceptual data.
Summary analysis for auditory–perceptual data.×
Variable BASE–POST BASE–FUP
BASE POST NP p χ2 BASE FUP NP p χ2
P1
Overall loudness 2 14* 5 .004 11.14 9 2 10 .066 5.43
Loudness variability 2 11 8 .050 6.0 9 2 10 .066 5.43
Overall pitch 0 13* 8 .002 12.28 8 1 12* .012 8.86
Pitch variability 0 13* 8 .002 12.28 11* 1 9 .018 8.0
Overall voice quality 2 14* 5 .004 11.14 11 2 8 .050 6.0
Articulatory precision 1 19* 1 .000 30.86 8 4 9 .368 2.0
P2
Overall loudness 1 12* 1 .000 15.39 4 14* 3 .005 10.57
Loudness variability 2 11* 1 .002 13.0 8 13* 0 .002 12.27
Overall pitch 3 6 5 .607 1.0 3 10 8 .156 3.71
Pitch variability 2 10* 2 .010 9.14 4 13* 4 .021 7.71
Overall voice quality 1 9* 4 .030 7.0 3 14* 4 .005 10.57
Articulatory precision 0 4 10* .004 10.86 0* 11 10 .005 10.57
P3
Overall loudness 2 14* 5 .004 11.14 10 8 3 .156 3.71
Loudness variability 2 14* 5 .004 11.14 3 13* 5 .018 8.0
Overall pitch 0 8 13* .002 12.29 1 5 15* .001 14.86
Pitch variability 1 11* 9 .018 8.0 0* 11 10 .005 10.57
Overall voice quality 1 12* 8 .012 8.86 1 13* 7 .006 10.29
Articulatory precision 0 14* 7 .001 14.0 5 7 9 .565 1.14
P4
Overall loudness 1 19* 1 .000 30.86 0 16* 5 .000 19.14
Loudness variability 0 18* 3 .0001 26.57 0 17* 4 .000 22.57
Overall pitch 0 13* 8 .002 12.29 2 6 13* .012 8.86
Pitch variability 0 11* 10 .005 10.57 2 7 12* .028 7.14
Overall voice quality 0 20* 1 .0001 36.28 2 17* 2 .000 21.42
Articulatory precision 0 14* 7 .0009 14.0 1* 11 9 .018 8.0
P5
Overall loudness 1 3 17* .000 21.74 4 4 13* .021 7.71
Loudness variability 1 4 16* .000 18.0 5 5 11 .180 3.43
Overall pitch 1 3 17* .000 21.71 3 6 12* .050 6.0
Pitch variability 1 6 14* .002 12.29 4 6 11 .156 3.71
Overall voice quality 3 5 13* .018 8.00 3 8 10 .156 3.71
Articulatory precision 1 3 17* .000 21.74 6 3 12* .050 6.0
Note.For each perceptual variable, there were a total of 21 choices (3 Sentence Pairs × 7 Listeners) for each comparison BASE to POST and BASE to FUP (with the exception of P2 for POST). The values represent the number of listeners who preferred either a BASE, POST, FUP, or NP speech sample. Boldfaced and asterisked values indicate the preference (BASE, POST, FUP, or NP) that was statistically significant. P4 repeated only single words versus the entire sentence in this task. POST = posttreatment; FUP = follow-up; NP = no preference.
Note.For each perceptual variable, there were a total of 21 choices (3 Sentence Pairs × 7 Listeners) for each comparison BASE to POST and BASE to FUP (with the exception of P2 for POST). The values represent the number of listeners who preferred either a BASE, POST, FUP, or NP speech sample. Boldfaced and asterisked values indicate the preference (BASE, POST, FUP, or NP) that was statistically significant. P4 repeated only single words versus the entire sentence in this task. POST = posttreatment; FUP = follow-up; NP = no preference.×
Table 2. Summary analysis for auditory–perceptual data.
Summary analysis for auditory–perceptual data.×
Variable BASE–POST BASE–FUP
BASE POST NP p χ2 BASE FUP NP p χ2
P1
Overall loudness 2 14* 5 .004 11.14 9 2 10 .066 5.43
Loudness variability 2 11 8 .050 6.0 9 2 10 .066 5.43
Overall pitch 0 13* 8 .002 12.28 8 1 12* .012 8.86
Pitch variability 0 13* 8 .002 12.28 11* 1 9 .018 8.0
Overall voice quality 2 14* 5 .004 11.14 11 2 8 .050 6.0
Articulatory precision 1 19* 1 .000 30.86 8 4 9 .368 2.0
P2
Overall loudness 1 12* 1 .000 15.39 4 14* 3 .005 10.57
Loudness variability 2 11* 1 .002 13.0 8 13* 0 .002 12.27
Overall pitch 3 6 5 .607 1.0 3 10 8 .156 3.71
Pitch variability 2 10* 2 .010 9.14 4 13* 4 .021 7.71
Overall voice quality 1 9* 4 .030 7.0 3 14* 4 .005 10.57
Articulatory precision 0 4 10* .004 10.86 0* 11 10 .005 10.57
P3
Overall loudness 2 14* 5 .004 11.14 10 8 3 .156 3.71
Loudness variability 2 14* 5 .004 11.14 3 13* 5 .018 8.0
Overall pitch 0 8 13* .002 12.29 1 5 15* .001 14.86
Pitch variability 1 11* 9 .018 8.0 0* 11 10 .005 10.57
Overall voice quality 1 12* 8 .012 8.86 1 13* 7 .006 10.29
Articulatory precision 0 14* 7 .001 14.0 5 7 9 .565 1.14
P4
Overall loudness 1 19* 1 .000 30.86 0 16* 5 .000 19.14
Loudness variability 0 18* 3 .0001 26.57 0 17* 4 .000 22.57
Overall pitch 0 13* 8 .002 12.29 2 6 13* .012 8.86
Pitch variability 0 11* 10 .005 10.57 2 7 12* .028 7.14
Overall voice quality 0 20* 1 .0001 36.28 2 17* 2 .000 21.42
Articulatory precision 0 14* 7 .0009 14.0 1* 11 9 .018 8.0
P5
Overall loudness 1 3 17* .000 21.74 4 4 13* .021 7.71
Loudness variability 1 4 16* .000 18.0 5 5 11 .180 3.43
Overall pitch 1 3 17* .000 21.71 3 6 12* .050 6.0
Pitch variability 1 6 14* .002 12.29 4 6 11 .156 3.71
Overall voice quality 3 5 13* .018 8.00 3 8 10 .156 3.71
Articulatory precision 1 3 17* .000 21.74 6 3 12* .050 6.0
Note.For each perceptual variable, there were a total of 21 choices (3 Sentence Pairs × 7 Listeners) for each comparison BASE to POST and BASE to FUP (with the exception of P2 for POST). The values represent the number of listeners who preferred either a BASE, POST, FUP, or NP speech sample. Boldfaced and asterisked values indicate the preference (BASE, POST, FUP, or NP) that was statistically significant. P4 repeated only single words versus the entire sentence in this task. POST = posttreatment; FUP = follow-up; NP = no preference.
Note.For each perceptual variable, there were a total of 21 choices (3 Sentence Pairs × 7 Listeners) for each comparison BASE to POST and BASE to FUP (with the exception of P2 for POST). The values represent the number of listeners who preferred either a BASE, POST, FUP, or NP speech sample. Boldfaced and asterisked values indicate the preference (BASE, POST, FUP, or NP) that was statistically significant. P4 repeated only single words versus the entire sentence in this task. POST = posttreatment; FUP = follow-up; NP = no preference.×
×
Table 3. Summary analysis for acoustic data.
Summary analysis for acoustic data.×
Variable Grand means
BASE–POST
BASE–FUP
BASE POST FUP TP Visual STAT ES Visual STAT ES
P1
Max performance “ah” 2.4 3.5 4.4 16.1 p < .12a 1.1 p < .035a 2.0
Duration (s) (1.0) (1.0) (0.5) (2.8)
Max performance 200 436 301 884 p < .01a 5.6 p < .17a 2.4
F0 range (Hz) (42) (139) (45) (234)
Sustained phonation 87.4 87.4 87.4 96.5 p < .0001b 0.0 p < .0001b 0.0
dB SPL of 3 longest “ahs” (4.9) (2.9) (7.2) (1.3)
Sustained phonation 22.1 22.9 24.1 26.3 N/A 0.3 N/A 0.8
HNR of 3 longest “ahs” (2.3) (0.7) (0.8) (0.1)
Sentence repetition 75.0 76.4 76.0 74.9 N/A 0.9 N/A 0.6
dB SPL (1.6) (1.3) (0.74) (3.6)
Sentence repetition 62 76 66 96.1 N/A 2.0 N/A 0.6
F0 range (Hz) (7) (3) (16) (49)
P2
Max performance “ah” 1.8 5.7 7.0 11.4 p < .001a 6.5 p < .0001a 5.2
Duration (s) (0.6) (0.4) (1.4) (0.6)
Max performance 289 724 1097 2242 p < .0001b 2.0 p < .0001b 3.8
F0 range (Hz) (215) (147) (61)
Sustained phonation 86.3 94.6 99.4 95.3 p < .0001a 5.5 p < .0001a 8.7
dB SPL of 3 longest “ahs” (1.5) (1.1) (1.0) (2.3)
Sustained phonation 22.0 22.0 24.0 27.9 p < .87a 0.0 p < .451a 0.9
HNR of 3 longest “ahs” (2.3) (2.8) (1.3) (1.6)
Sentence repetition 73.0 82.0 83.5 78.6 p < .005a 4.7 p < .002a 5.5
dB SPL (1.9) (0.4) (4.4) (0.4)
Sentence repetition 109 131 225 180 p < .23a 1.4 p < .003a 7.3
F0 range (Hz) (16) (23) (26) (29)
P3
Max performance “ah” 5.3 6.8 13.4 15.7 p < .05a 1.9 p < .001a 10.1
Duration (s) (0.8) (0.6) (1.0)
Max performance 796 633 1005 2853 p < .14a −1.3 p < .07a 1.6
F0 range (Hz) (127) (112) (48)
Sustained phonation 82.4 84.2 87.2 93.9 N/A 0.7 N/A 1.8
dB SPL of 3 longest “ahs” (2.7) (2.8) (2.6)
Sustained phonation 19.2 21.7 23.3 26.4 N/A 0.5 N/A 0.8
HNR of 3 longest “ahs” (4.9) (0.5) (4.0)
Sentence repetition 80.4 79.3 82.9 74.4 p < .861a −0.4 p < .626a 0.4
dB SPL (2.9) (2.9) (3.7)
Sentence repetition 118 128 134 107 N/A 0.6 N/A 0.9
F0 Range (Hz) (18) (32) (38)
P4
Max performance “ah” 1.0 1.2 1.5 16.9 N/A 0.3 N/A 0.7
Duration (s) (0.7) (0.2) (0.4) (0.1)
Max performance 137 211 185 1638 p < .0001b 2.2 p < .0001b 1.4
F0 range (Hz) (34) (21) (18) (1099)
Sustained phonation 83.1 87.5 89.4 94.3 N/A 0.4 N/A 0.6
dB SPL of 3 longest “ahs” (10.1) (2.5) (1.4) (0.5)
Sustained phonation 15.6 19.3 24.5 26.8 p < .17a 0.8 p < .03a 2.0
HNR of 3 longest “ahs” (4.4) (2.0) (0.7) (0.5)
Sentence repetition 70.4 75.0 76.8 75.7 p < .001b 1.1 p < .001b 1.5
dB SPL (4.4) (0.7) (0.6)
Sentence repetition 34 42 52 118 N/A 0.4 N/A 1.0
F0 range (Hz) (18) (9) (6)
P5
Max performance “ah” 6.7 7.4 7.3 15.8 N/A 0.5 N/A 0.4
Duration (s) (1.4) (1.3) (0.8) (5.3)
Max performance 860 519 719 1066 p < .02a −2.3 p < .24a −0.1
F0 range (Hz) (146) (81) (69) (110)
Sustained phonation 95.1 91.2 95.3 99.7 p < .20a −2.8 p < .95a 0.1
dB SPL of 3 longest “ahs” (1.4) (5.04) (4.2) (3.6)
Sustained phonation 22.6 22.9 21.7 28.9 N/A 0.1 N/A −0.2
HNR of 3 longest “ahs” (4.7) (0.5) (2.47) (0.2)
Sentence repetition 78.9 78.5 78.4 86.9 N/A −0.2 N/A −0.2
dB SPL (2.4) (1.9) (2.5) (0.1)
Sentence repetition 132 106 96 165 N/A −0.7 N/A −0.9
F0 range (Hz) (38) (8) (141) (0.7)
Note.Mean data across BASE, POST, FUP, and TP are presented with SDs in parentheses. Effect sizes were calculated using a Cohen's (1988)  d statistic modified by Busk and Serlin (1992) . Direction of arrows and triangles reflects direction of change (“up” indicating improvements, “down” indicating worsening). TP = typically developing peer; Visual = summary of the visual trend analysis; STAT = results of the statistical analysis, if applied; ▴ or ▾ = visual trends with nonoverlapping data points; ↑ or ↓ = visual trends with overlapping data points; — = no visual trend in the data, including instances of variable baseline data; HNR = harmonics-to-noise ratio; N/A = statistics not applied.
Note.Mean data across BASE, POST, FUP, and TP are presented with SDs in parentheses. Effect sizes were calculated using a Cohen's (1988)  d statistic modified by Busk and Serlin (1992) . Direction of arrows and triangles reflects direction of change (“up” indicating improvements, “down” indicating worsening). TP = typically developing peer; Visual = summary of the visual trend analysis; STAT = results of the statistical analysis, if applied; ▴ or ▾ = visual trends with nonoverlapping data points; ↑ or ↓ = visual trends with overlapping data points; — = no visual trend in the data, including instances of variable baseline data; HNR = harmonics-to-noise ratio; N/A = statistics not applied.×
a p value derived through analysis of variance.
p value derived through analysis of variance.×
b p value derived through split-middle binomial probability test.
p value derived through split-middle binomial probability test.×
Table 3. Summary analysis for acoustic data.
Summary analysis for acoustic data.×
Variable Grand means
BASE–POST
BASE–FUP
BASE POST FUP TP Visual STAT ES Visual STAT ES
P1
Max performance “ah” 2.4 3.5 4.4 16.1 p < .12a 1.1 p < .035a 2.0
Duration (s) (1.0) (1.0) (0.5) (2.8)
Max performance 200 436 301 884 p < .01a 5.6 p < .17a 2.4
F0 range (Hz) (42) (139) (45) (234)
Sustained phonation 87.4 87.4 87.4 96.5 p < .0001b 0.0 p < .0001b 0.0
dB SPL of 3 longest “ahs” (4.9) (2.9) (7.2) (1.3)
Sustained phonation 22.1 22.9 24.1 26.3 N/A 0.3 N/A 0.8
HNR of 3 longest “ahs” (2.3) (0.7) (0.8) (0.1)
Sentence repetition 75.0 76.4 76.0 74.9 N/A 0.9 N/A 0.6
dB SPL (1.6) (1.3) (0.74) (3.6)
Sentence repetition 62 76 66 96.1 N/A 2.0 N/A 0.6
F0 range (Hz) (7) (3) (16) (49)
P2
Max performance “ah” 1.8 5.7 7.0 11.4 p < .001a 6.5 p < .0001a 5.2
Duration (s) (0.6) (0.4) (1.4) (0.6)
Max performance 289 724 1097 2242 p < .0001b 2.0 p < .0001b 3.8
F0 range (Hz) (215) (147) (61)
Sustained phonation 86.3 94.6 99.4 95.3 p < .0001a 5.5 p < .0001a 8.7
dB SPL of 3 longest “ahs” (1.5) (1.1) (1.0) (2.3)
Sustained phonation 22.0 22.0 24.0 27.9 p < .87a 0.0 p < .451a 0.9
HNR of 3 longest “ahs” (2.3) (2.8) (1.3) (1.6)
Sentence repetition 73.0 82.0 83.5 78.6 p < .005a 4.7 p < .002a 5.5
dB SPL (1.9) (0.4) (4.4) (0.4)
Sentence repetition 109 131 225 180 p < .23a 1.4 p < .003a 7.3
F0 range (Hz) (16) (23) (26) (29)
P3
Max performance “ah” 5.3 6.8 13.4 15.7 p < .05a 1.9 p < .001a 10.1
Duration (s) (0.8) (0.6) (1.0)
Max performance 796 633 1005 2853 p < .14a −1.3 p < .07a 1.6
F0 range (Hz) (127) (112) (48)
Sustained phonation 82.4 84.2 87.2 93.9 N/A 0.7 N/A 1.8
dB SPL of 3 longest “ahs” (2.7) (2.8) (2.6)
Sustained phonation 19.2 21.7 23.3 26.4 N/A 0.5 N/A 0.8
HNR of 3 longest “ahs” (4.9) (0.5) (4.0)
Sentence repetition 80.4 79.3 82.9 74.4 p < .861a −0.4 p < .626a 0.4
dB SPL (2.9) (2.9) (3.7)
Sentence repetition 118 128 134 107 N/A 0.6 N/A 0.9
F0 Range (Hz) (18) (32) (38)
P4
Max performance “ah” 1.0 1.2 1.5 16.9 N/A 0.3 N/A 0.7
Duration (s) (0.7) (0.2) (0.4) (0.1)
Max performance 137 211 185 1638 p < .0001b 2.2 p < .0001b 1.4
F0 range (Hz) (34) (21) (18) (1099)
Sustained phonation 83.1 87.5 89.4 94.3 N/A 0.4 N/A 0.6
dB SPL of 3 longest “ahs” (10.1) (2.5) (1.4) (0.5)
Sustained phonation 15.6 19.3 24.5 26.8 p < .17a 0.8 p < .03a 2.0
HNR of 3 longest “ahs” (4.4) (2.0) (0.7) (0.5)
Sentence repetition 70.4 75.0 76.8 75.7 p < .001b 1.1 p < .001b 1.5
dB SPL (4.4) (0.7) (0.6)
Sentence repetition 34 42 52 118 N/A 0.4 N/A 1.0
F0 range (Hz) (18) (9) (6)
P5
Max performance “ah” 6.7 7.4 7.3 15.8 N/A 0.5 N/A 0.4
Duration (s) (1.4) (1.3) (0.8) (5.3)
Max performance 860 519 719 1066 p < .02a −2.3 p < .24a −0.1
F0 range (Hz) (146) (81) (69) (110)
Sustained phonation 95.1 91.2 95.3 99.7 p < .20a −2.8 p < .95a 0.1
dB SPL of 3 longest “ahs” (1.4) (5.04) (4.2) (3.6)
Sustained phonation 22.6 22.9 21.7 28.9 N/A 0.1 N/A −0.2
HNR of 3 longest “ahs” (4.7) (0.5) (2.47) (0.2)
Sentence repetition 78.9 78.5 78.4 86.9 N/A −0.2 N/A −0.2
dB SPL (2.4) (1.9) (2.5) (0.1)
Sentence repetition 132 106 96 165 N/A −0.7 N/A −0.9
F0 range (Hz) (38) (8) (141) (0.7)
Note.Mean data across BASE, POST, FUP, and TP are presented with SDs in parentheses. Effect sizes were calculated using a Cohen's (1988)  d statistic modified by Busk and Serlin (1992) . Direction of arrows and triangles reflects direction of change (“up” indicating improvements, “down” indicating worsening). TP = typically developing peer; Visual = summary of the visual trend analysis; STAT = results of the statistical analysis, if applied; ▴ or ▾ = visual trends with nonoverlapping data points; ↑ or ↓ = visual trends with overlapping data points; — = no visual trend in the data, including instances of variable baseline data; HNR = harmonics-to-noise ratio; N/A = statistics not applied.
Note.Mean data across BASE, POST, FUP, and TP are presented with SDs in parentheses. Effect sizes were calculated using a Cohen's (1988)  d statistic modified by Busk and Serlin (1992) . Direction of arrows and triangles reflects direction of change (“up” indicating improvements, “down” indicating worsening). TP = typically developing peer; Visual = summary of the visual trend analysis; STAT = results of the statistical analysis, if applied; ▴ or ▾ = visual trends with nonoverlapping data points; ↑ or ↓ = visual trends with overlapping data points; — = no visual trend in the data, including instances of variable baseline data; HNR = harmonics-to-noise ratio; N/A = statistics not applied.×
a p value derived through analysis of variance.
p value derived through analysis of variance.×
b p value derived through split-middle binomial probability test.
p value derived through split-middle binomial probability test.×
×
Table 4. Parents' perceptual ratings of their child's voice, speech, and communication “most of the time.”
Parents' perceptual ratings of their child's voice, speech, and communication “most of the time.”×
Perceptual characteristic Difference scores in parent perceptual ratings
P1
P2
P3
P4
P5
B − P B − F B − P B − F B − P B − F B − P B − F B − P B − F
Always loud enough 44 5 39 40 33 23 32 8
Never nasal voice 8 −2 11 13 4 1 −18 14
Never hoarse, scratchy voice 20 22 1 2 6 2 −31 26
Never monotone 5 −7 32 38 3 15 6 −1
Never breathy voice 31 2 39 39 22 12 1 6
Never strained voice 17 −19 7 5 28 19 −2 −2
Always speaks so others can understand 18 −10 20 24 13 0 −9 −30
Always talks when playing with kids 18 71 3 5 17 −2 0 −11
Always starts talking with other kids 23 72 7 5 14 2 −22 −10
Never frustrated when talking 23 10 −3 −5 26 13 25 −2
Note.B − P is the difference score in percentage rating from BASE to POST; B − F is the difference score in percentage rating from BASE to FUP. Positive values reflect improved perceptions; negative values reflect worsening perceptions.
Note.B − P is the difference score in percentage rating from BASE to POST; B − F is the difference score in percentage rating from BASE to FUP. Positive values reflect improved perceptions; negative values reflect worsening perceptions.×
Table 4. Parents' perceptual ratings of their child's voice, speech, and communication “most of the time.”
Parents' perceptual ratings of their child's voice, speech, and communication “most of the time.”×
Perceptual characteristic Difference scores in parent perceptual ratings
P1
P2
P3
P4
P5
B − P B − F B − P B − F B − P B − F B − P B − F B − P B − F
Always loud enough 44 5 39 40 33 23 32 8
Never nasal voice 8 −2 11 13 4 1 −18 14
Never hoarse, scratchy voice 20 22 1 2 6 2 −31 26
Never monotone 5 −7 32 38 3 15 6 −1
Never breathy voice 31 2 39 39 22 12 1 6
Never strained voice 17 −19 7 5 28 19 −2 −2
Always speaks so others can understand 18 −10 20 24 13 0 −9 −30
Always talks when playing with kids 18 71 3 5 17 −2 0 −11
Always starts talking with other kids 23 72 7 5 14 2 −22 −10
Never frustrated when talking 23 10 −3 −5 26 13 25 −2
Note.B − P is the difference score in percentage rating from BASE to POST; B − F is the difference score in percentage rating from BASE to FUP. Positive values reflect improved perceptions; negative values reflect worsening perceptions.
Note.B − P is the difference score in percentage rating from BASE to POST; B − F is the difference score in percentage rating from BASE to FUP. Positive values reflect improved perceptions; negative values reflect worsening perceptions.×
×