Factors Influencing the Prediction of Speech Intelligibility Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Sarah Yoho Leopold, B. A. Graduate Program in Speech and Hearing Science The Ohio State University 2016 Dissertation Committee: Eric W. Healy, Advisor Rachael Frush Holt DeLiang Wang © Copyright by Sarah Yoho Leopold 2016 Abstract The three manuscripts presented here examine the relative importance of various ‘critical bands’ of speech, as well as their susceptibility to the corrupting influence of background noise. In the first manuscript, band-importance functions derived using a novel technique are compared to the standard functions given by the Speech Intelligibility Index (ANSI, 1997). The functions derived with the novel technique show a complex ‘microstructure’ not present in previous functions, possibly indicating an increased accuracy of the new method. In the second manuscript, this same technique is used to examine the effects of individual talkers and types of speech material on the shape of the band-importance functions. Results indicate a strong effect of speech material, but a smaller effect of talker. In addition, the use of ten talkers of different genders appears to greatly diminish any effect of individual talker. In the third manuscript, the susceptibility to noise of individual critical bands of speech was determined by systematically varying the signal-to-noise ratio in each band. The signal-to-noise ratio that resulted in a criterion decrement in intelligibility for each band was determined. Results from this study indicate that noise susceptibility is not equal across bands, as has been assumed. Further, noise susceptibility appears to be independent of the relative importance of each band. Implications for future applications of these data are discussed. ii Dedication Dedicated to my mother, who instilled in me strength, resilience, and a lifetime love of learning. iii Acknowledgements Foremost, I would like to thank my advisor, Eric Healy, for his immeasurable and invaluable support and guidance throughout my graduate studies. Without his encouragement and direction, I would not be where I am today. I can never adequately express my gratitude. I would also like to extend a special thank you to my dissertation committee members- Rachael Frush Holt and DeLiang Wang. They were both integral in my growth and success during my graduate career. I have a very special place in my heart for my laboratory colleagues, who have been there for me both professionally and personally. Carla Youndahl and Frederic Apoux have been great colleagues and even better friends. A sincere thank you to Brittney Carter, Jordan Vasko, and Shuang Liu. There have been several other individuals who have made my time at Ohio State both successful and truly enjoyable. There are many, but my gratitude especially to Janet Weisenberger, Robert Fox, Jason Johnson, Gail Whitelaw, Christy Goodman, Pete Eichel, Christina Roup, Lawrence Feth, Yuxuan Wang, and Jitong Chen. Lastly, and no less importantly, I want to thank my family. Their support through the years has allowed me to follow my heart and spend the time and effort necessary to succeed. To my husband, Jordan, who has prioritized my career and happiness above all else- thank you. My love and endless gratitude to my father, Brad, my brother, Matt, my uncle, John, and my grandparents iv John and Barbara. And lastly, I want to acknowledge the decades of love and unwavering encouragement shown to me by my late mother, Lynn. She always made me believe that what I did was special and worthwhile, and I would be nowhere without the confidence and strength she instilled in me. v Vita January 6, 1988……………………………………...Born 2009…………………………………………………B.A. Speech and Hearing Science, The Ohio State University Columbus, Ohio 2009 - 2015…………………………………………Graduate Research Associate Speech Psychoacoustics Laboratory The Ohio State University Columbus, OH 2009 - 2015…………………………………………Graduate Teaching Associate Dept. of Speech and Hearing Science The Ohio State University Columbus, OH 2015…………………………………………………Presidential Fellow The Ohio State University Columbus, OH Publications Healy, E.W., Yoho, S.E., Chen, J., Wang, Y. & Wang, D.L. (2015). An algorithm to increase speech intelligibility for hearing-impaired listeners in novel segments of the same noise type. Journal of the Acoustical Society of America, 138, 1660-1669. Apoux, F., Youngdahl, C.L., Yoho, S.E., & Healy, E.W. (2015). Dual-carrier processing to convey temporal fine structure cues: Implications for cochlear implants. Journal of the Acoustical Society of America, 138, 1469-1480. Healy, E. W., Yoho, S. E., Wang, Y., Apoux, F., & Wang, D.L. (2014). Speech-cue transmission by an algorithm to increase consonant recognition in noise for hearing- impaired listeners. Journal of the Acoustical Society of America, 136, 3325-3336. vi Mandel, M. I., Yoho, S. E., Healy, E. W. (2014). Generalizing time-frequency importance functions across noises, talkers, and phonemes. Proceedings of INTERSPEECH 2014, 2016-2020. Healy, E. W., Yoho, S. E., Wang, Y., & Wang, D. L. (2013). An algorithm to improve speech recognition in noise for hearing-impaired listeners. Journal of the Acoustical Society of America, 134, 3029-3038. Apoux, F., Yoho, S. E., Youngdahl, C. L., & Healy, E. W. (2013). Role and relative contribution of temporal envelope and fine structure cues in sentence recognition by normal-hearing listeners. Journal of the Acoustical Society of America, 134, 2205-2212. Healy, E. W., Yoho, S. E., Youngdahl, C. L., & Apoux, F. (2013). Talker effects in speech band importance functions. Proceedings of Meetings on Acoustics, 19, 050066, pp. 1-6. Apoux, F., Yoho, S. E., Youngdahl, C. L., & Healy, E. W. (2013). Can envelope recovery account for speech recognition based on temporal fine structure? Proceedings of Meetings on Acoustics, 19, 050072, pp.1-6. Healy, E. W., Yoho, S. E., & Apoux, F. (2013). Band importance for sentences and words reexamined. Journal of the Acoustical Society of America, 133, 463-473. Field of Study Major Field: Speech and Hearing Science vii Table of Contents Abstract…………………………………………………………………………..………..ii Dedication………………………………………………………………….…….……….iii Acknowledgements………………………………………………………….…….….…..iv Vita…………………………………………………………………………………..……vi List of Tables…………………………………………………………………….…….....xi List of Figures……………………………………………………………….………...…xii Chapter 1: Introduction………………………………………………...………………….1 Chapter 2: Review of Literature………………………………………………….…….…4 I. Normal Speech Perception………………………………………...……….…...4 II. Auditory Filters…………………………………………………………….......5 III. Spectral and Temporal Speech Information …………………….…………....6 IV. Glimpsing Theory of Speech Perception…………………………………….10 V. Effects of Sensorineural Hearing Impairment…………………….……….…11 A. Impact of Spectral Processing Deficits ……..………………………..12 B. Other Deficits and Their Impacts …………………………………….15 C. Specific Factors for Speech Perception in Hearing Impaired Listeners ……………………………………………………………………………18 VI. Articulation Index/Band Importance Functions…………………..…………22 A. Assumptions and Considerations……………..…………..…………..25 B. Band Importance Functions…………………….....………………….28 C. Techniques for Deriving Band Importance Functions…………..……30 Chapter 3: Overview of Current Studies……………………………………...…...……..49 Chapter 4: Manuscript 1: Band Importance Functions Reexamined…………………....51 I. Introduction………………………………………...………….........................53 viii II. Experiment 1. High- and Low- Predictability SPIN Sentences……….……...58 A. Method……………………………………………………………….58 1. Subjects………………………………………………………58 2. Stimuli ……………………………………………………….59 3. Procedure…………………………………………………….61 B. Results………………………………………………………………...63 III. Experiment 2. Phonetically-Balanced Words ……………….………………68 A. Method……………………………………………………………….68 1. Subjects………………………………………………………68 2. Stimuli and Procedure………………………………………..69 B. Results………………………………………………………………...70 IV. Discussion……………………………………………………………………74 V. Summary and Conclusions…………………………………….………...……82 Chapter 5: Manuscript 2: Talker and Speech Material Effects in Band Importance Functions…………………………………………………………………...…………….94 I. Introduction………………………………………...……………….................96 II. Experiment 1. Single vs. Ten-Talker Sentences……………..……………...101 A. Method………………………………………………………..…….101 1. Subjects……………………………………………….…….101 2. Stimuli and Procedure…………………………………..….102 B. Results……………………………………………………………….105 III. Experiment 2. Different Talkers…………… ……………….……………..107 A. Method………………………………………………………..…….107 1. Subjects……………………………………………….…….107 2. Stimuli and Procedure………………………………………108 B. Results………………………………………………………………110 ix IV. Experiment 3. Different Materials…………… ……………….…………...111 A. Method……………………………………………………………...111 1. Subjects……………………………………………………..111 2. Stimuli and Procedure………………………………………112 B. Results……………………………………………………………….113 IV. Discussion…………………………………………………………………..114 Chapter 6: Manuscript 3: Noise Susceptibility of Speech Critical Bands…...……...….128 I. Introduction……………..………………………………...……………….....130 II. Method………………………………………….……………..……..……...134 A. Subjects………………………………………………………….….134 B. Stimuli………………………………………………………………134 C. Procedure……………………………………………………...……135 1. Band Importance Method……………………….………….135 2. Noise Susceptibility Method……………………………….136 III. Results …………………………………………..…………….…..………..138 IV. Discussion………………………………………………………………….143 V. Summary and Conclusions…….……………….…………….……………..147