ACOUSTIC CHARACTERISTICS OF ARABIC FRICATIVES By MOHAMED ALI AL-KHAIRY A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2005 Copyright 2005 by Mohamed Ali Al-Khairy To my father who did not live to see the fruit of his work. ACKNOWLEDGMENTS After finishing writing this dissertation on a rainy summer night I decided not to bother with a lengthy acknowledgment section. After all I was the one who wrote it. Well, leaving ego and false pride aside, this work could not have been done without the help of many. First and foremost, thanks go to The Almighty GOD for His guidance and blessings without which graduate school would have been a worse nightmare. My gratitude goes also to my wonderful supervisor and mentor Dr. Ratree Wayland whose dedication to her students, teaching, and research is beyond highest expectations. Without her help, guidelines, constant encouragement, and support, this work would not have been possible. Members of my supervisory committee (Dr. Gillian Lord and Dr. Caroline Wiltshire from Linguistics, and Dr. Rahul Shirvastav from Communication Sciences and Disorders) were of the utmost help in the process of finishing this work. My stay in Gainesville introduced me to many people. Most were nice and cheerful and some one could definitively live without. I will skip the latter group to save space. However, among such nice and wonderful people I got to know during this journey are the wonderful students, faculty, and staff of the Linguistics Department who were of tremendous help both personally and academically. My special thanks and gratitude go also to Dr. Aida Bamia and Dr. Haig Der-Houssikian from the Department of African and Asian Languages and Literature. Their supervision, friendship, and encouragement went far beyond the responsibilities of mentors to those of parents. For that I will be eternally grateful. I also would like to thank my study partners, Yousef Al-Dlaigan, who was unjustly forced to change his career, and AbdulWaheed Al-Saadi, who was brave enough iv to finish his Ph.D. I regret to say that I am still unclear of the process of gene transformation in strawberry and citrus. I hope though you learned from me how to read a spectrogram. I tried my best. Now is the fun part: thanking my friends in the phonetics lab. Listed in chronological order of their liberation from school are Rebecca Hill, Jodi Bray, Philip Monahan, Sang-Hee Yeon, HeeNam Park, Victor Prieto, and Manjula Shinge. Yet to feel the wonderful breeze outside Turlington basement are my great friends Andrea Dallas, Bin Li, and Priyankoo Sarmah. I thank them for all the cheerful moments and laughs we shared at the University of Florida. Although life might take us into different routes, our friendship is eternal. Although they are in a different time zone, I thank my friends on the west cost and across the Atlantic for their great advice and emotional support, without which long nights would definitely have been longer. I will send them my phone bills later. I am sure that I left out some names; for those unintentionally missed I extend my apologies and sincere thanks. The acoustic analyses in this dissertaion were carried out in a timely manner thanks to the existence of the wonderful free PRAAT program and the abundant help and suggestion from its authors and the PRAAT user community. Also, I was extremely fortunate to escape the nightmare of typesetting using the popular- but-not-really-friendly commercial software. I thank Ron Smith for making his ufthesis LATEX class freely available. Across oceans and continents, the prayers and encouragement of my parents and siblings were a driving force and endless motivation to finish and join them back home. Although God had other plans for my father and older brother, I am sure they are proud of what their prayers from high above have accomplished. Finally, words fall short in describing my gratitude and thanks toward my wife, Nadaa; and kids, Faisal and Farah. They have suffered through this dissertation v almost as much as I have; maybe even more. Through the many nights I spent at the lab, they have shown endless patience, love, and understanding. I truly cannot imagine having gone through this process without such amazing love and support. Parts of this work were supported by a McLaughlin Dissertation Fellowship from the College of Liberal Arts and Sciences, University of Florida. vi TABLE OF CONTENTS page ACKNOWLEDGMENTS ............................. iv LIST OF TABLES ................................. ix LIST OF FIGURES ................................ x ABSTRACT .................................... xii CHAPTER 1 INTRODUCTION .............................. 1 2 LITERATURE REVIEW .......................... 5 2.1 Introduction .............................. 5 2.2 Fricative Production ......................... 5 2.3 Acoustic Cues to Fricative Place of Articulation .......... 7 2.3.1 Amplitude Cues ........................ 7 2.3.2 Duration Cues ......................... 13 2.3.3 Spectral Cues ......................... 15 2.3.4 Formant Transition Cues ................... 22 2.4 Studies of Arabic Fricatives ..................... 26 3 METHODOLOGY .............................. 29 3.1 Data Collection ............................ 29 3.1.1 Participants .......................... 29 3.1.2 Materials ............................ 30 3.1.3 Recording ........................... 30 3.2 Data Analysis ............................. 31 3.2.1 Segmentation of Speech .................... 31 3.2.2 Acoustic Analyses ....................... 34 3.3 Statistical Analyses .......................... 40 4 AMPLITUDE AND DURATION ...................... 42 4.1 Amplitude Measurements ....................... 42 4.1.1 Normalized Frication Noise RMS Amplitude ........ 42 4.1.2 Relative Amplitude of Frication Noise ............ 45 vii 4.2 Temporal Measurements ....................... 56 4.2.1 Absolute Duration of Frication Noise ............ 56 4.2.2 Normalized Duration of Frication Noise ........... 59 5 SPECTRAL MEASUREMENTS ...................... 63 5.1 Spectral Peak Location ........................ 63 5.2 Spectral Moments ........................... 69 5.2.1 Spectral Mean ......................... 71 5.2.2 Spectral Variance ....................... 74 5.2.3 Spectral Skewness ....................... 80 5.2.4 Spectral Kurtosis ....................... 89 6 FORMANT TRANSITION ......................... 96 6.1 Second Formant (F 2) at Transition ................. 96 6.2 Locus Equation ............................ 100 7 STATISTICAL CLASSIFICATION OF FRICATIVES .......... 102 7.1 Discriminant Function Analysis ................... 102 7.2 Classification Accuracy of DFA ................... 103 7.3 Classification Power of Predictors .................. 105 7.4 Classification Results ......................... 105 8 GENERAL DISCUSSION .......................... 111 8.1 Temporal Measurement ........................ 112 8.2 Amplitude Measurement ....................... 113 8.3 Spectral Measurement ........................ 115 8.4 Transition Information ........................ 118 8.5 Discriminant Analysis ......................... 119 8.6 Conclusion ............................... 120 REFERENCES ................................... 121 BIOGRAPHICAL SKETCH ............................ 127 viii LIST OF TABLES Table page 1–1 Arabic Fricatives .............................. 3 4–1 Relative Amplitude: Vowel Context ................... 48 4–2 Mean Relative Amplitude ......................... 53 5–1 Spectral Peak Location .......................... 65 5–2 Spectral Moments ............................. 72 5–3 Spectral Skewness: Significant Contrasts for Voiced Fricatives ..... 86 5–4 Spectral Skewness: Significant Contrasts for Voiceless Fricatives .... 86 6–1 Second Formant at Transition ...................... 97 6–2 Locus Equation: Slope and y-intercept .................. 101 7–1 Prior Probabilities for Group Membership ................ 103 7–2 Variance Accounted for by DFA Functions ................ 104 7–3 Overall Voiceless Classification ...................... 107 7–4 Cross-Validated Classification Results .................. 107 7–5 Overall Voiced Classification ....................... 109 7–6 Cross-Validated Voiced Classification .................. 109 7–7 Overall Voiceless Classification ...................... 109 7–8 Cross-Validated Voiceless Classification ................. 110 ix LIST OF FIGURES Figure page 3–1 Example of Segmentation ......................... 32 3–2 Segmentation of /Q/ ........................... 33 3–3 Hamming vs. Kaiser Window ...................... 35 3–4 Duration .................................. 36 4–1 Frication Noise RMS Amplitude ..................... 43 4–2 Frication Noise RMS Amplitude: Vowel Context ............ 44 4–3 Frication Noise RMS Amplitude: Place and Voicing .......... 45 4–4 Relative Amplitude ............................ 47 4–5 Relative Amplitude: Place and Voicing ................. 49 4–6 Relative Amplitude; Place and Short Vowels .............. 51 4–7 Relative Amplitude; Place and Long Vowels .............. 52 4–8 Relative Amplitude: Voicing and Short Vowels ............. 54 4–9 Relative Amplitude: Voicing and Long Vowels ............. 55 4–10 Fricative Duration: Place and Voicing .................. 57 4–11 Fricative Duration: Place and Voicing Interactions ........... 58 4–12 Fricative Duration: Vowel Context .................... 59 4–13 Normalized Frication Noise: Place and Voicing