University of Wisconsin Milwaukee UWM Digital Commons Theses and Dissertations August 2013 Acoustic Characteristics of Tense and Lax Vowels Across Sentence Position in Clear Speech Lindsay Kayne Roesler University of Wisconsin-Milwaukee Follow this and additional works at: https://dc.uwm.edu/etd Part of the Other Rehabilitation and Therapy Commons Recommended Citation Roesler, Lindsay Kayne, "Acoustic Characteristics of Tense and Lax Vowels Across Sentence Position in Clear Speech" (2013). Theses and Dissertations. 754. https://dc.uwm.edu/etd/754 This Thesis is brought to you for free and open access by UWM Digital Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of UWM Digital Commons. For more information, please contact [email protected]. ACOUSTIC CHARACTERISTICS OF TENSE AND LAX VOWELS ACROSS SENTENCE POSITION IN CLEAR SPEECH by Lindsay Roesler A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in Communication Sciences and Disorders at The University of Wisconsin-Milwaukee August 2013 ABSTRACT ACOUSTIC CHARACTERISTICS OF TENSE AND LAX VOWELS ACROSS SENTENCE POSITION IN CLEAR SPEECH by Lindsay Roesler The University of Wisconsin-Milwaukee, 2013 Under the Supervision of Professor Jae Yung Song The purpose of this study was to examine the acoustic characteristics of tense and lax vowels across sentence positions in clear speech. Recordings were made of 12 participants reading monosyllabic target words at varying positions within semantically meaningful sentences. Acoustic analysis was completed to determine the effects of Style (clear vs. conversational), Tenseness (tense vs. lax), and Position (sentence-medial vs. sentence-final) on vowel duration, vowel space area, vowel space dispersion, and vowel peripheralization. The results showed speakers had longer durations and expanded vowel spaces in clear speech for both tense and lax vowels. Importantly, the amount of increase was similar for tense and lax vowels suggesting the defining properties of lax vowels (i.e., short duration and centralization) were manipulated in clear speech. A significant main effect of position for lax vowel space expansion showed greater vowel spaces for lax vowels in sentence-medial position in clear speech. Clear speech vowel adaptations appear to be dynamic with both vowel-specific and general transformations. ii © Copyright by Lindsay Roesler, 2013 All Rights Reserved iii TABLE OF CONTENTS 1. Introduction ..................................................................................................................... 1 1.1 Clear Speech History .................................................................................................... 2 2. Background ..................................................................................................................... 3 2.1 Speaking Fundamental Frequency Range ..................................................................... 5 2.2 Speaking Rate ............................................................................................................... 7 2.3 Vowel Lengthening ..................................................................................................... 11 2.4 Vowel Space Expansion ............................................................................................. 13 2.4.1 Vowel Space Area ............................................................................................ 14 2.4.2 Vowel Space Dispersion ................................................................................... 17 2.4.3 Vowel Peripheralization ................................................................................... 19 3. Vowel Production and Source Filter Theory ................................................................ 21 4. Vowel Classifications ................................................................................................... 23 5. Dialectal Variation ........................................................................................................ 25 6. Goals ............................................................................................................................. 26 6.1 Rationale ..................................................................................................................... 26 6.2 Purpose ........................................................................................................................ 28 7. Methods......................................................................................................................... 29 7.1 Listeners ...................................................................................................................... 29 7.2 Speaker Subjects ......................................................................................................... 30 7.3 Equipment ................................................................................................................... 30 7.4 Procedure .................................................................................................................... 31 7.5 Stimuli ......................................................................................................................... 33 7.6 Data ............................................................................................................................. 36 7.7 Acoustic Coding.......................................................................................................... 37 7.7.1 Durational Coding ............................................................................................ 37 7.7.2 Formant Coding ................................................................................................ 38 8. Results ........................................................................................................................... 41 8.1 Vowel Duration ........................................................................................................... 41 8.2 Vowel Space Area....................................................................................................... 47 8.3 Vowel Space Dispersion ............................................................................................. 50 8.4 Vowel Peripheralization.............................................................................................. 57 iv 9. Discussion ..................................................................................................................... 61 9.1 Summary of Results and Comparison to Previous Research ...................................... 61 9.1.1 Vowel Duration ................................................................................................ 64 9.1.2 Vowel Space Area ............................................................................................ 65 9.1.3 Vowel Space Dispersion ................................................................................... 66 9.1.4 Vowel Peripheralization ................................................................................... 67 9.2 Theoretical Implications ............................................................................................. 68 9.3 Limitations .................................................................................................................. 69 9.4 Future Research .......................................................................................................... 70 References ......................................................................................................................... 72 Appendices ........................................................................................................................ 77 Appendix A: Listener Consent Form ................................................................................ 77 Appendix B: Listener Scripts ............................................................................................ 78 Appendix C: Recruitment Flyers ...................................................................................... 79 Appendix D: Consent ........................................................................................................ 80 Appendix E: IRB approval................................................................................................ 87 Appendix F: Short Questionnaire ..................................................................................... 88 Appendix G: Hearing Screening ....................................................................................... 89 Appendix H: Dialect Screening ........................................................................................ 90 Appendix I: Dialect Screening Data Sheet ....................................................................... 91 Appendix J: Stimuli .......................................................................................................... 92 v LIST OF FIGURES Figure 1. Vowel space area in conversational (conv.) and clear speech (Figure adapted from Smiljanic and Bradlow, 2005).................................................................................. 15 Figure 2. Vowel space dispersion in conversational and clear speech (Figure adapted from Smiljanic and Bradlow, 2005).................................................................................. 18 Figure 3. Vowel peripheralization for /i/ (Figure adapted from Smiljanic and