Effect of Single-Channel Compression on Temporal Speech Information Although syllabic compression systems are available in many currently marketed hearing aids, the benefit of such systems continues to be debated. The goal of this study was to determine the effect of single-channel amplitude compression on use of speech information by listeners with hearing impairment. Effects on both temporal and ... Research Article
Research Article  |   October 01, 1996
Effect of Single-Channel Compression on Temporal Speech Information
 
Author Affiliations & Notes
  • Pamela E. Souza
    Speech and Hearing Sciences Department University of Washington Seattle
  • Christopher W. Turner
    Department of Speech Pathology and Audiology University of Iowa Iowa City
  • Contact author: Pamela E. Souza, PhD, Speech and Hearing Sciences Department, University of Washington, 1417 NE 42nd Street, Seattle, WA 98105
    Contact author: Pamela E. Souza, PhD, Speech and Hearing Sciences Department, University of Washington, 1417 NE 42nd Street, Seattle, WA 98105×
Article Information
Hearing & Speech Perception / Hearing Disorders / Hearing Aids, Cochlear Implants & Assistive Technology / Speech, Voice & Prosody / Hearing / Research Articles
Research Article   |   October 01, 1996
Effect of Single-Channel Compression on Temporal Speech Information
Journal of Speech, Language, and Hearing Research, October 1996, Vol. 39, 901-911. doi:10.1044/jshr.3905.901
History: Received September 5, 1995 , Accepted April 24, 1996
 
Journal of Speech, Language, and Hearing Research, October 1996, Vol. 39, 901-911. doi:10.1044/jshr.3905.901
History: Received September 5, 1995; Accepted April 24, 1996

Although syllabic compression systems are available in many currently marketed hearing aids, the benefit of such systems continues to be debated. The goal of this study was to determine the effect of single-channel amplitude compression on use of speech information by listeners with hearing impairment. Effects on both temporal and spectral information were considered, with particular focus on temporal cues. Speech recognition scores were assessed under four conditions, using two types of speech materials. Both temporal and spectral information were provided in the FullSpeech or natural speech stimuli. Unlike previous studies in which use of temporal information may have been confounded by spectral changes, in this study the listener's ability to use temporal information was tested directly using signal-correlated noise (SCN) stimuli, which consisted of a time-varying speech envelope modulating a broad-band noise carrier. Two conditions (FullSpeech and SCN) retained their natural amplitude characteristics. In two corresponding conditions the same stimuli were compressed digitally, using compression parameters appropriate for syllabic compression. This compression reduced the range of time-intensity variations. Recognition scores were obtained from listeners with mild-to-severe sensorineural loss and from a control group of listeners with normal hearing. All stimuli were presented at high levels to reduce potential effects of reduced audibility. Additionally, short-term speech level measurements were compared to individual listener's hearing thresholds to determine the range of speech levels in each frequency region that was audible for each stimulus condition. Results demonstrated no effect of compression on recognition scores for either the FullSpeech or SCN signals for listeners with normal hearing or listeners with hearing loss. This suggests that single-channel syllabic compression processing, of the type used in this study, does not alter the temporal (or spectral) signal sufficiently to cause decreased recognition for VCV syllables when speech audibility is maintained.

Acknowledgments
The authors wish to acknowledge two anonymous reviewers for comments on an earlier version of this manuscript and Dianne Van Tasell for her helpful comments throughout. We also wish to thank Tim Trine, Jim Chan, and Eduardo Solessario for assistance in developing the compression algorithm. This research was supported in part by NIH grant #DC00377.
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