Production and Perception of Tones in Cantonese Continuous Speech ,,：二 、 WONGT-¥ing Wai � ”j A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Philosophy in Linguistics •The Chinese University of Hong Kong January 2007 The Chinese University of Hong Kong holds the copyright of this thesis. Any person(s) intending to use a part or whole of the materials in the thesis in a proposed publication must seek copyright release from the Dean of the Graduate School. 0 3 M 18 )|| ~UNIVERSITY N^bXjJBRAnY SYSTEMyy^ Thesis/Assessment Committee Prof. Wang Shi Yuan William (Chair) Prof. Lee Hun Tak Thomas (Thesis Supervisor) Prof. Jiang-King Ping (Committee Member) Prof. Zee Yun Yang Eric (External Examiner) ACKNOWLEDGEMENT This thesis topic would not exist without my thesis supervisor, Thomas Lee, who whole-heartedly provided guidance and invaluable advice throughout the whole duration of my research. With his knowledge in linguistics and many related fields, I was able to broaden my horizon of knowing about language from different perspectives. I am also grateful to William Wang and Eric Zee for generously allowing me to join their weekly research seminars. Through collaborative atmosphere from their research groups, I could have my knowledge foundation solidified and gain many insightful comments on my own study. For my migration to the field of linguistics, I thank Gladys Tang, my previous thesis supervisor when I was pursuing an MA degree in Linguistics. Only through interaction with her could I have an invaluable chance to be exposed to sign language: manifestation of communication ability of human beings in the visual-gestural modality. Thanks must go to Yi Xu, who gave many helpful comments at design stages of some of the experiments conducted. Thanks to my classmates in the graduate school of the Department of Linguistics and Modern Languages, who shared every moment of learning, chatting and entertaining with me. I am also indebted to researchers and colleagues at Language Acquisition Laboratory and Language Engineering Laboratory at Chinese University of Hong Kong as well as Phonetics Laboratory at City University of Hong Kong, for providing me with intellectual support and sharing their thoughts on my own experiments. I am indebted to numerous anonymous subjects who voluntarily served in both tone production and perception studies in this study, indirectly helping me in generalizing observations drawn in this thesis. Though always from a distance, my parents and my two brothers always showed their unfailing concern and love，which were essential in my facing different i stages of work towards producing this thesis. I am also indebted to my dearest wife, Heidi, who tried hard to maintain a warm and harmonious environment for my thesis writing. Last but not least, with every success and failure, I know God is always leading my way. Without my heavenly Father, even single bits of this study would never exist. ii ABSTRACT By means of experimental methods, we studied in this thesis asymmetries related to Cantonese tones in continuous speech, from both production and perception perspectives. First, a tone production task (Experiment 1) was carried out to obtain the Fo movements corresponding to six basic Cantonese tones in citation form. The obtained acoustic data were evaluated against tone-letter label proposals by different scholars, leading to the observation that Bauer & Benedict's (1997) system provides the most accurate picture of Cantonese tones. With disyllabic tonal sequences (Experiment 2), we investigated contextual tonal variations (inter-tonal Fo influences) of Cantonese tones in both forward (carryover) and backward (anticipatory) directions. Specifically, contextual variation due to carryover effect is larger than that due to anticipatory effect, resulting in a production asymmetry that the second half of a syllable shows a smaller magnitude of Fo variations across different tonal contexts. Based on this directional asymmetry, tone perception experiments (Experiments 3 and 4) were conducted to arrive at the perceptual asymmetry that the second half of a syllable is more salient for identifying tones in continuous speech. Two further experiments were then administered to generalize this observation to (1) syllables with different intensity profiles and (2) contour tones. It was found that intensity plays a minor yet noticeable role underlying the perceptual bias (Experiment 5)，as a drop in bias from 93.23% to 77.44% was reflected when intensity was increased at the onset portion of the target syllable. For contour tones, the second half of a syllable was found again more heavily relied on than the first half in tone perception (Experiment 6). Zooming out from experimental details, the observed asymmetries in tone production and perception were argued to be compatible with a number of language phenomena like tone-spreading typology and contour tone distribution restrictions. Finally, discussion on possible new research questions and how our findings are related to language acquisition and language change studies were presented. iii 摘要 於本論文中，我們以聲調發音及感知實驗的方法調查有關粵語聲調在連續語流 中的不對稱現象。首先，我們透過實驗一取得對應粵語中六個聲調獨立出現時 的基頻曲線，並以之與不同學者提出的聲調字母(tone-letter)系統作比對，總括 Bauer & Benedict (1997)的系統最能代表粤語不同的聲調°在實驗二中’我們以 雙音節作爲發音材料硏究粤語聲調在不同連讀環境中基頻曲線的變化。我們發 現前進式作用(carryover effect)比後退式作用(anticipatory effect)對基頻的影響爲 大，導致於連續語流中，每一音節的後半部分受連讀環境的影響比前半部分爲 小。基於這個方向不對稱性，實驗三及四證實於連續語流中聲調感知較側重每 一音節的後半部分。爲求證這聲調感知的不對稱現象是否在不同的音強模式以 及升降調中成立，我們另外進行了兩個跟進實驗。實驗五證實音強對聲調感知 的側重情況起一定作用，例如當目標音節前半部分的音強被加大時，側重率從 93.23%降至77.44%�實驗六則證實了目標音節的後半部分支配著升降調的感 知。綜觀以上實驗結果，我們提出不同的語言現象均能與之兼容，像聲調展開 類型學(tone-spreading typology)及升降調分佈限制(contour tone distribution restrictions)等。最後，我們討論我們的實驗結果如何與語言習得及語言演變連 接並提出基於我們實驗結果的新硏究問題。 iv CONTENTS ACKNOWLEDGEMENT I ABSTRACT III 摘要 IV CONTENTS v CHAPTER 1 INTRODUCTION 1 CHAPTER 2 TONES IN CONTINUOUS SPEECH 4 2.1 Production of tones 4 2.2 Perception of tones 7 CHAPTER 3 TONE PRODUCTION 9 3.1 Tones in isolation - Experiment 1 9 Introduction 10 Material 10 Recording and Fq extraction 10 Results and discussion 11 3.2 Tones in context - Experiment 2 13 Introduction 14 Material 15 Recording and Fq extraction 16 Results - Anticipatory effect 17 Results - Carryover effect 18 Results - Pitch target computation 20 Results - Magnitude of variation 21 3.3 Discussion 22 Relative magnitude of contextual variations 23 Cantonese T4 in context 24 Further generalizations 25 3.4 Summary of findings 27 V CHAPTER 4 TONE PERCEPTION 28 4.1 Temporal distribution of tonal information - Expt. 3 and 4 29 Experiment 3 - Stimulus recording 29 Experiment 3 - Stimulus preparation 31 Experiment 3 — Procedure 31 Experiment 3 - Results 32 Experiment 4 - Stimulus preparation 33 Experiment 4 - Procedure 34 Experiment 4 - Results 34 4.2 Effect of intensity - Experiment 5 36 Stimulus preparation 37 Procedure 38 Results - Tone identification responses 38 Results - Effect of intensity 40 4.3 Contour tone perception - Experiment 6 43 Stimulus preparation 43 Procedure 44 Results 44 4.4 Summary of findings 46 CHAPTER 5 CONCLUSIONS AND DISCUSSION 47 5.1 Tone Production 47 Typology of tone rules 48 Acquisition of tone production 49 5.2 Tone Perception 50 Evidence from Speech Production Phenomena 50 Role of the first half 52 Acquisition of tone perception 53 BIBLIOGRAPHY 56 vi CHAPTER 1 INTRODUCTION One of the perplexing problems in human language studies is the mapping between categorical units in our mind and continuous speech signals in the physical world. Human speech makes use of phonemes, which are discrete, as the basic units to convey information. However, when investigated under acoustic instrument, speech signals are transmitted in the form of air pressure perturbation patterns, which are continuous in nature. The difficulty of describing the mapping lies in inevitable existence of variations due to different factors along the articulatory-auditory pathway. At the articulation stage, different physiological characteristics of articulators of the vocal tract across speakers, for instance, lead to speech sounds with much inter-speaker variation, given the same phoneme in ones' mind. Peterson & Barney (1952) conducted a seminal study to demonstrate the considerable amount of formant frequency variation and heavy overlap of categories in vowel samples produced by subjects of different age and sex. Second, environmental noise level and transfer functions of communication medium are good examples at the transmission stage contributing to distortion of speech signals. Audibility of speech sounds deteriorates rapidly in an environment with high noise level. Similarly, band-pass filtering of speech signals over telephone transmission channels (especially in mobile telephones) leaves speech signals with low resemblance to the original natural speech. Finally, at the audition stage, certain components of speech waveform stimulating our ears cannot reach our brain due to masking effects. On top of these, there are still intra-speaker factors like time of the day (Garrett & Healey，1987), emotion (Chuenwattanapranithi etal, 2006), sentential position due to downdrift (Ohala, 1978) 1 and speaking rate (Miller et al., 1986; Zee, 2002; Wong, 2006c) which further introduce phonetic variations into speech signals even if they are produced by the same speaker. This thesis reports a series of experiments to unveil factors participating in the mapping from linguistic tones to their acoustical form (with focus on fundamental frequency! (F。))，with Cantonese� as the target