Towards Development of Intelligibility Assessment for Dysphonic Speech
Keiko Ishikawa · OhioLink ETD Center (Ohio Library and Information Network) · 2017
Dysphonia affects one's ability to produce voice.Because voice is the most fundamental component of speech, it is not surprising that many speakers with dysphonia report decreased intelligibility in everyday communication environments.Despite this report, intelligibility is not routinely measured in clinical assessment of dysphonia.Because the intelligibility deficit is most noticeable in noisy environments, measuring the deficit requires thorough understanding of the interaction between dysphonia, background noise and intelligibility.Understanding this interaction would also help development of treatment approaches for maximizing intelligibility for chronically dysphonic patients.The objective of this project was to establish experimental models for investigating this interaction.In particular, potential of perceptual and acoustic approaches were examined.The overarching goal of this research is to develop a clinical tool for assessment of intelligibility in dysphonic speech and treatment approaches for improving the intelligibility deficit.Two speech perception experiments were conducted to determine the effect of background noise on intelligibility.The first study measured intelligibility with a transcriptionbased method in quiet and noise.The second study measured intelligibility with a rating-based method in three levels of noise.Correlation between these measurements was examined to evaluate their agreement.The results indicated that these measurements strongly correlate; however, their relationship with ratings of voice quality significantly differed.These findings indicate that both of these measures could be used to evaluate intelligibility of dysphonic speech; however, they are not equivalent measures.vi I also would like to thank Dr. Noah Silbert for kindly opening his laboratory for my experiments.He has also given me a number of advices on analysis of perception data.His expertise and experience in psychoacoustics were vital to completion of this project.I am also deeply indebted to Dr. Joel MacAuslan for his guidance on acoustic analysis.The works that are related Landmark-based analysis would have not been completed without his brilliant work on SpeechMark®