CATEGORIZATION OF SILENT INTERVALS IN PARKINSONIAN SPEECH: A STUDY OF PAUSE Anna C. Gravelin A Thesis Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 2017 Committee: Jason A. Whitfield, Advisor Ronald Scherer Brent Archer © 2017 Anna C. Gravelin All Rights Reserved iii ABSTRACT Jason A. Whitfield, Advisor Parkinson Disease (PD) is a neurodegenerative disease that affects the function of the basal ganglia, which affects both speech and non-speech movements. Examining silent intervals may be an important diagnostic feature of speech impairment severity, because a number of studies indicate individuals with PD exhibit differences in the proportion, frequency, and duration of pause as compared to control speakers. The goal of the current investigation was to determine the extent to which silent intervals in the speech of individuals with PD differ from healthy controls relative to linguistic and phonemic contexts. Silent intervals as short as 15 ms in duration were identified in speech samples of speakers with and without PD. Each interval was categorized relative to the surrounding syntactic and phonemic environment. Compared to control speakers, individuals with PD exhibited significantly longer silent intervals between words at locations that were syntactically unrelated. Additionally, silent intervals that were preceded by a stop or followed by a fricative or sonorant were significantly longer for speakers with PD than controls. Finally, speakers with PD produced significantly fewer stop gaps than controls. The results of this study indicate that individuals with PD exhibit differences in the distribution of silent intervals related to phonemic, rather than linguistic boundaries, likely reflecting deficits in speech motor timing associated with PD. iv This thesis is dedicated in memory of my grandparents, Walter and Roberta Bolthouse. v ACKNOWLEDGMENTS There are many individuals I would like to acknowledge for their support during the completion of this project. First and foremost, I must sincerely thank my parents, Nancy and Craig Gravelin, without whom this project would not have been possible. Their unwavering love, support, and guidance has instilled in me a confidence and tenacity I carry with me every day. Thank you to my sister, Kristen, and brother, Nick, for their love and support at every point in my educational career. I also acknowledge my grandma, Laura Gravelin, and my aunts, uncles, and cousins for their encouragement. To my dearest friends, Megan Andrews and Hannah Geiger: your friendship the past two years has been remarkable. I am overwhelmingly grateful for the support and care you both so generously showed me throughout my Master’s career and in the completion of this project. To my close friend and colleague, Zoe Kriegel: thank you for your abundant encouragement and belief in my capacity to learn and grow as a person, mentor, student, and professional. To my dear friend, Ashlei Castillo: I cherish our nearly 20 years of friendship and thank you for your continual support at every step in my journey. I thank my friends Mike and Natalie Trent and my fellow classmates Christina Dick, Courtney Wrentmore, Lisa Raab, Rachel Rutherford, Jake Baker, Sarah Starcher, Nicole Moore, Ashleigh Stanfield, Alexa Wiebusch, and Sadie Sneider for their encouragement and helping hands along the way. Lastly, my sincerest thanks to those individuals who assisted me in the completion of this project. To my advisor and mentor, Dr. Jason Whitfield: Thank you for your integral guidance, patience, support, and investment in my success as a student and professional over the past two years. Thank you to Tarynn Clune and Cassidy Quinlan, who assisted me in calculating reliability. I also acknowledge and thank my committee members, Drs. Ronald Scherer and Brent Archer for their input and guidance in the completion of this project. vi TABLE OF CONTENTS Page CHAPTER I: INTRODUCTION ........................................................................................... 1 Speech Production ..................................................................................................... 1 Pause ............................................................................................................ 2 Short silent intervals in speech .......................................................... 3 Stop gaps ................................................................................... 3 Longer silent intervals in speech....................................................... 4 Parkinson Disease ..................................................................................................... 5 Speech Production in Parkinson Disease ................................................................... 6 Articulation in Parkinson Disease .................................................................. 6 Prosody in Parkinson Disease ........................................................................ 8 Measurement of Pause: Methodological Considerations ........................................... 8 Silent intervals in the speech of individuals with Parkinson Disease ............ 9 Aims of the Current Paper ......................................................................................... 13 CHAPTER II: METHOD ...................................................................................................... 14 Participants ................................................................................................................. 14 Protocol ...................................................................................................................... 16 Measures .................................................................................................................... 18 Syntactic boundaries ...................................................................................... 19 Phonemic boundaries ..................................................................................... 22 Reliability ................................................................................................................... 22 Statistics ..................................................................................................................... 23 vii CHAPTER III: RESULTS ..................................................................................................... 24 Overall Measures of Speech Rate and Percent Pause ................................................ 24 Effect of Syntactic Boundary Type............................................................................ 25 Comparison of Between-Word and Within-Word Intervals ...................................... 31 Effect of Preceding Phoneme Manner ....................................................................... 32 Effect of Subsequent Phoneme Manner ..................................................................... 35 CHAPTER IV: DISCUSSION .............................................................................................. 42 Silent Intervals Associated with Syntactic Boundaries ............................................. 42 Between- and Within-Word Intervals ........................................................................ 43 Effect of Preceding Phoneme Manner on Silent Interval Duration ........................... 45 Effect of Subsequent Phoneme Manner on Silent Intervals: Stop Gaps .................... 45 Methodological Notes ................................................................................................ 46 Limitations ................................................................................................................. 46 REFERENCES ...................................................................................................................... 48 APPENDIX A. HUMAN SUBJECTS REVIEW BOARD APPROVAL LETTER ............. 56 APPENDIX B. CATERPILLAR PASSAGE: BETWEEN-WORD SYNTACTIC BOUNDARIES ...................................................................................................................... 57 APPENDIX C. OCCURRENCE OF PRECEDING PHONEME MANNER CATEGORIES BY PARTICIPANT...................................................................................................................... 58 APPENDIX D. OCCURRENCE OF SUBSEQUENT PHONEME MANNER CATEGORIES BY PARTICIPANT ............................................................................................................... 59 viii LIST OF FIGURES Figures Page 1 Histogram of log-transformed duration of identified silent intervals for the control and Parkinson Disease groups, Adapted from Whitfield et al., 2015 ............ 13 2 Annotated waveform and spectrogram of an example of a silent interval associated with a major syntactic boundary ............................................................... 21 3 Distribution of between-word silent intervals before and after log transformation for the control and Parkinson Disease groups ................................... 27 4 Distribution of silent intervals by syntactic boundary type for the control and Parkinson Disease groups .......................................................................................... 28 5 Fixed effect estimates and standard error for the duration of short silent intervals preceded by stops, fricatives, and sonorants for the control and Parkinson Disease groups ..........................................................................................................