The Impact of Lexical Characteristics and Noise on Intelligibility of Parkinsonian Speech Purpose This study investigated the impact of lexical characteristics on the intelligibility of speakers with Parkinson's disease (PD). Intelligibility was compared for listening in a quiet versus a noisy environment. Method A total of 192 young listeners participated in the study, with 96 listeners listening in quiet and ... Research Article
Research Article  |   April 17, 2018
The Impact of Lexical Characteristics and Noise on Intelligibility of Parkinsonian Speech
 
Author Affiliations & Notes
  • Yi-Fang Chiu
    Department of Communication Sciences and Disorders, Saint Louis University, MO
  • Karen Forrest
    Department of Speech and Hearing Sciences, Indiana University Bloomington
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication.×
  • Correspondence to Yi-Fang Chiu: yifang.chiu@health.slu.edu
  • Editor-in-Chief: Julie Liss
    Editor-in-Chief: Julie Liss×
Article Information
Speech, Voice & Prosodic Disorders / Dysarthria / Hearing & Speech Perception / Acoustics / Special Populations / Older Adults & Aging / Speech / Research Articles
Research Article   |   April 17, 2018
The Impact of Lexical Characteristics and Noise on Intelligibility of Parkinsonian Speech
Journal of Speech, Language, and Hearing Research, April 2018, Vol. 61, 837-846. doi:10.1044/2017_JSLHR-S-17-0205
History: Received May 31, 2017 , Revised September 25, 2017 , Accepted December 26, 2017
 
Journal of Speech, Language, and Hearing Research, April 2018, Vol. 61, 837-846. doi:10.1044/2017_JSLHR-S-17-0205
History: Received May 31, 2017; Revised September 25, 2017; Accepted December 26, 2017

Purpose This study investigated the impact of lexical characteristics on the intelligibility of speakers with Parkinson's disease (PD). Intelligibility was compared for listening in a quiet versus a noisy environment.

Method A total of 192 young listeners participated in the study, with 96 listeners listening in quiet and 96 listening in noise in which the spoken sentences were mixed with 10-talker babble. The listeners transcribed spoken sentences with target words controlled for word frequency and neighborhood density. The sentences were produced by 12 speakers with PD and 12 healthy control (HC) speakers. Transcription accuracy was compared across lexical categories between PD and HC and between the two listening conditions.

Results Transcription accuracy was higher for high-frequency words than low-frequency words for both speaker groups in quiet and in noise. The neighborhood density effect was evident only in the noise condition with better intelligibility for words from sparse neighborhoods than from dense neighborhoods. Regardless of listening condition, the PD group was less intelligible with a significant decrease in intelligibility in noise relative to quiet.

Conclusions The lexical properties of the words affected listeners' understanding of Parkinsonian speech. Frequent words in sparse neighborhood enhanced intelligibility, especially under adverse listening conditions. Babble noise had a detrimental impact on the intelligibility of Parkinsonian speech. The extent of the lexical effect on intelligibility increased in noise.

Acknowledgments
We would like to thank Dr. Yi Shen at Indiana University for the assistance in stimulus preparation, as well as Danielle Garrett for data collection.
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