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Pressures and Flows for a Convergent and Divergent Oblique Glottis of 15 Degrees

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Pressures and Flows for a Convergent and Divergent Oblique Glottis of 15 Degrees PRESSURES AND FLOWS FOR A CONVERGENT AND DIVERGENT OBLIQUE GLOTTIS OF 15 DEGREES Jason A. Whitfield, B.A. 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 May 2012 Committee: Ronald Scherer, Advisor John Folkins Roger Colcord © 2012 Jason A. Whitfield All Rights Reserved iii ABSTRACT Ronald Scherer, Advisor Current high-speed imaging of vocal fold motion has shown vibrational asymmetries in both individuals with and without voice disorders. However, empirical data regarding aerodynamic pressure of asymmetric glottal configurations is limited. The current investigation examined empirically derived intraglottal pressures of left-right glottal asymmetry (obliquity) using the static constant flow model, M5. Two cases, one convergent and one divergent, having an obliquity of 15o were examined. Seven diameters along with a range of transglottal pressure were studied for each case. For both cases of obliquity, when the diameter was small, the vocal folds were more aerodynamically entrained, with each vocal fold having similar intraglottal pressures. As the diameter increased, the aerodynamic coupling of the vocal folds decreased, leading to cross channel pressure differences at glottal entrance as large as 70% for the convergent Case I and 40% for the divergent Case II. These aerodynamic differences may potentially enhance out of phase motion of the vocal folds. These data suggest that the aerodynamic effects of obliquity are highly dependent on diameter and angle. Results from this study should be incorporated into multimass computer simulation models to further examine the dynamic effects of obliquity on vocal fold oscillation and glottal flow. iv This study is dedicated in memory of my Grandfather, Ray Albertson. v ACKNOWLEDGMENTS I would first like to thank my advisor, Ronald Scherer, for his time, guidance, and support during this portion of my graduate education. In addition, I want to thank my committee members, Roger Colcord and John Folkins for their time. Also, I want to thank Alexander Goberman for his support and guidance during the past two years. To my fellow Master’s students: thank you for your support and friendship as we completed this degree together. Thank you to Elina Banzina, Ramya Konnai, Sabiha Parveen, Siva Priya Santhanam, Lisa Shattuck, Eric Swartz, Stephanie Richards, and Elizabeth Witter for being good friends and office-mates. Thank you to Brianna Chapman, Katie Keenan, and Katharine Murphy for being such caring, supportive friends. To Charlie Hughes, thank you for your friendship and advice. Thank you to My Family: Mom, Granny, Dad, Karen, Greg, and Dee for your love and continuous support during my education and throughout my life. A most special and loving thank you to my wife Kathleen Whitfield; I could not have completed this phase of my education without your loving kindness and understanding. vi TABLE OF CONTENTS Page CHAPTER I. INTRODUCTION .......................................................................................... 1 Basic Overview of Phonation for Voice and Speech ................................................. 1 Vocal fold motion and glottal geometries ...................................................... 2 Clinical observations ...................................................................................... 3 Glottal obliquity ............................................................................................. 8 Overview of the Literature ......................................................................................... 9 Effect of diameter .......................................................................................... 11 Effect of glottal angle..................................................................................... 12 Effect of obliquity .......................................................................................... 12 Overview of the Current Study .................................................................................. 13 CHAPTER II. METHODS ................................................................................................... 15 Glottal Configurations for the Current Study ............................................................ 15 The M5 Model ........................................................................................................... 17 Setting Up the Model for Data Collection ................................................................. 20 Measurement of Flow ................................................................................................ 23 Calibration Procedures ............................................................................................... 25 Calibration of the pressure transducers .......................................................... 26 Calibration of the pneumotach with the flowmeter ....................................... 27 Data Collection with Model M5 ................................................................................ 28 Presentation of the Data ............................................................................................. 34 vii CHAPTER III: RESULTS .................................................................................................... 37 Case I: Convergent Glottis; -20o Conv. Side and +10o Div. Side; Oblique 15o ........ 37 Normalized pressure distributions ................................................................. 38 Glottal entrance pressures .............................................................................. 39 Summary of flow data .................................................................................... 59 Case II: Divergent Glottis; -10o Conv. Side and +20o Div. Side; Oblique 15o .......... 64 Normalized pressure distributions ................................................................. 65 Glottal entrance pressures .............................................................................. 67 Bimodal pressure distributions ...................................................................... 71 Summary of flow data .................................................................................... 97 CHAPTER IV: DISCUSSION ............................................................................................. 103 Similar Observation between Cases........................................................................... 103 Differences between Cases ........................................................................................ 104 Extension and Comparison of the Findings ............................................................... 105 Comparison of oblique data with symmetric data ......................................... 106 Small diameters: 0.005 to 0.04 cm..................................................... 107 General overview ...................................................................... 107 Case I ........................................................................................ 109 Case II ....................................................................................... 110 Large diameters: 0.08 to 0.32 cm ....................................................... 111 Case I ........................................................................................ 111 Case II ....................................................................................... 116 Effect of obliquity .............................................................................. 122 viii Replication Comparisons ............................................................................... 122 CHAPTER V: CONCLUSIONS .......................................................................................... 126 REFERENCES .......................................................................................................... 129 APPENDIX A. ............................................................................................................ 133 Pressure Transducer Calibration ................................................................................ 133 APPENDIX B. .......................................................................................................... 138 Comparison of the Oblique Glottis to the Symmetric ............................................... 138 Case I .......................................................................................................... 138 Case II ........................................................................................................... 152 ix LIST OF FIGURES Figure Page 1 A normal cycle of vocal fold vibration as view in the mid-coronal plane ................. 4 2 Case I: A convergent glottis of -10 degrees with an obliquity angle of 15 degrees .. 16 3 Case II: A divergent glottis of +10 degrees with an obliquity angle of 15 degrees ... 16 4 Model M5 and its components ................................................................................... 17 5 Schematic diagram of M5 .......................................................................................... 18 6 Locations of the pressure taps on a vocal fold piece ................................................. 19 7 Pressure taps on the vocal fold inserts ....................................................................... 21 8 Schematic representation of the setup for model M5 ................................................ 24 9 Mounted Flowmeter
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