Active Research Projects

This is an incomplete list of current projects.

Pragmatics Projects

Syntax Projects

Phonetics Projects

Cross-linguistic differences in focus encoding

with Szu-wei Chen, Taiwan, and Bei Wang, Beijing - To explore how focus is differentially encoded in the speech of monolingual Taiwanese, Taiwan Mandarin and Beijing Mandarin speakers, and Taiwanese and Mandarin bilinguals. Preliminary results show systematic differences among these languages/dialects.

Dates:2007-. Funded by:Collaborative.

Researchers: Yi Xu,

Maximum speed of articulation

Testing the Near Ceiling Performance hypothesis - To test the NCP hypothesis proposed in Xu (2007): Due to its vital importance for the survival and wellbeing of human individuals, speech is maintained near an overall performance ceiling, and such near-ceiling performance is a major source of variability in speech.

Dates:2001-. Funded by:Internal.

Researchers: Yi Xu,

Multiple effects of consonant manner of articulation and intonation type on F0 in English

with Andrew Wallace, Brown University, USA - To explore the acoustic characteristics and underlying mechanisms of consonantal perturbation of F0 contours in connected speech.

Dates:2005-. Funded by:c.

Researchers: Yi Xu,

Nature of tone sandhi in Mandarin

with Maolin Wang, Jinan University, China - To explore the nature of the L-tone sandhi in Mandarin. We will re-examine some of the existing claims about this tone sandhi phenomenon.

Dates:2006-. Funded by:Collaborative.

Researchers: Yi Xu,

Neural network simulation of acquisition of tone and focus based on unsupervised learning with Self Organizing Map (SOM)

with Rushen Shi and Bruno Gauthier, University of Quebec, Canada - To explore how infants may derive phonetic categories from adult input with no formal instructions, through unsupervised learning simulated by self-organizing maps. The finding so far is that almost perfect categorization of the four Mandarin tones produced in continuous speech can be achieved by unsupervised learning, with continuous F0 velocity profiles as the input. The findings suggest that a) velocity profiles are largely free of idiosyncratic variability, b) they directly reflect articulatory movements toward the underlying targets of the four tones as described by the target approximation model (Xu & Wang, 2001), c) the unsupervised learning process can achieve categorization with continuous acoustic parameters as direct input, and nowhere in the process is feature extraction needed.

Dates:2004-. Funded by:Collaborative.

Researchers: Yi Xu,

Prosodic cues for syllable grouping in Mandarin

with Maolin Wang, Jinan University, China - To examine how syllable grouping, as an independent communicative function, is encoded in parallel with other functions in Mandarin.

Dates:2003-. Funded by:Collaborative.

Researchers: Yi Xu,

Prosodic encoding of new topic in Mandarin

with Bei Wang, Beijing, China

Dates:2004-.

Researchers: Yi Xu,

Prosody of questions in English and Mandarin

with Fang Liu, University of Chicago, USA - To investigate question intonation in Mandarin and English by controlling tone, lexical-stress pattern and focus. The findings so far are consistent with the functional view of intonation, according to which components of intonation are defined and organized by individual communicative functions that are independent of each other but are encoded in parallel.

Dates:2003-. Funded by:Collaborative.

Researchers: Yi Xu,

Quantitative modeling of tone and intonation

with Santitham Prom-on and Bundit Thipakorn, King Mongkut’s University of Technology Thonburi, Thailand - To develop a quantitative Target Approximation (qTA) model for simulating F0 contours of speech. Following the articulatory-functional framework of the PENTA model (Xu, 2005), the qTA model simulates the production of tone and intonation as a process of syllable-synchronized sequential target approximation. In the model, tone and intonation are treated as communicative functions that directly specify the parameters of the qTA model. The numerical values of the qTA will be extracted from natural speech via supervised learning. And the quality of the modeling output will be both numerically assessed and perceptually evaluated.

Dates:2005-. Funded by:Collaborative.

Researchers: Yi Xu,

Spoken Language Conversion with Accent Morphing

Spoken language conversion is the challenge of using synthesis systems to generate utterances in the voice of a speaker but in a language unknown to the speaker. Previous approaches have been based on voice conversion and voice adaptation technologies applied to the output of a foreign language TTS system. This inevitably reduces the quality and intelligibility of the output, since the source speaker will not be a good source of phonetic material in the new language. Our work contrasts previous work with a new approach that uses two synthesis systems: one in the source speaker's voice, one in the voice of a native speaker of the target language. Audio morphing technology is then exploited to correct the foreign accent of the source speaker, while at the same time trying to maintain his or her identity. In this project we aim to construct a spoken language conversion system using accent morphing and evaluate its performance in terms of intelligibility and speaker identity.

Dates:2006-.

Researchers: Mark Huckvale, Kayoko Yanagisawa,

The size code in the expression of anger and joy in speech

with Suthathip Chuenwattanapranithi, King Mongkut’s University of Technology Thonburi, Thailand - To test the “size code” hypothesis for encoding anger and joy in speech. According to the hypothesis, these two emotions are conveyed in speech by exaggerating or understating the body size of the speaker, just as nonhuman animals exaggerate or understate their body size to communicate threat or appeasement. We will conduct acoustic analysis of publicly available emotional speech databases, and synthesize Thai vowels with a 3D articulatory synthesizer using parameter manipulations suggested by the size code hypothesis, and asked Thai listeners to judge the body size and emotion of the speaker. Initial results are in support of the size code hypothesis.

Dates:2005-. Funded by:Collaborative.

Researchers: Yi Xu,

Timing and coordination in speech production

To test the hypothesis proposed in Xu (Lingua, in press), Xu & Liu (2006): The onset of the syllable, where consonant, vowel, tone and phonation register all start to approach their respective targets, provides a recurrent time marker with which timing can be controlled by the speaker and tracked by the listener.

Dates:2007-. Funded by:Internal.

Researchers: Yi Xu,

Speech & Hearing Science Projects

List of Completed Research Projects

Research Research Groups Research Projects Research Staff Publications Reports Working Papers in Linguistics Speech, Hearing and Language Books Annual PhD Day Seminars, Workshops, Lectures Current Events Past Events Speech Science Forum Reading Groups	Active Research Projects This is an incomplete list of current projects. Pragmatics Projects Syntax Projects Phonetics Projects Cross-linguistic differences in focus encoding with Szu-wei Chen, Taiwan, and Bei Wang, Beijing - To explore how focus is differentially encoded in the speech of monolingual Taiwanese, Taiwan Mandarin and Beijing Mandarin speakers, and Taiwanese and Mandarin bilinguals. Preliminary results show systematic differences among these languages/dialects. Dates:2007-. Funded by:Collaborative. Researchers: Yi Xu, Maximum speed of articulation Testing the Near Ceiling Performance hypothesis - To test the NCP hypothesis proposed in Xu (2007): Due to its vital importance for the survival and wellbeing of human individuals, speech is maintained near an overall performance ceiling, and such near-ceiling performance is a major source of variability in speech. Dates:2001-. Funded by:Internal. Researchers: Yi Xu, Multiple effects of consonant manner of articulation and intonation type on F0 in English with Andrew Wallace, Brown University, USA - To explore the acoustic characteristics and underlying mechanisms of consonantal perturbation of F0 contours in connected speech. Dates:2005-. Funded by:c. Researchers: Yi Xu, Nature of tone sandhi in Mandarin with Maolin Wang, Jinan University, China - To explore the nature of the L-tone sandhi in Mandarin. We will re-examine some of the existing claims about this tone sandhi phenomenon. Dates:2006-. Funded by:Collaborative. Researchers: Yi Xu, Neural network simulation of acquisition of tone and focus based on unsupervised learning with Self Organizing Map (SOM) with Rushen Shi and Bruno Gauthier, University of Quebec, Canada - To explore how infants may derive phonetic categories from adult input with no formal instructions, through unsupervised learning simulated by self-organizing maps. The finding so far is that almost perfect categorization of the four Mandarin tones produced in continuous speech can be achieved by unsupervised learning, with continuous F0 velocity profiles as the input. The findings suggest that a) velocity profiles are largely free of idiosyncratic variability, b) they directly reflect articulatory movements toward the underlying targets of the four tones as described by the target approximation model (Xu & Wang, 2001), c) the unsupervised learning process can achieve categorization with continuous acoustic parameters as direct input, and nowhere in the process is feature extraction needed. Dates:2004-. Funded by:Collaborative. Researchers: Yi Xu, Prosodic cues for syllable grouping in Mandarin with Maolin Wang, Jinan University, China - To examine how syllable grouping, as an independent communicative function, is encoded in parallel with other functions in Mandarin. Dates:2003-. Funded by:Collaborative. Researchers: Yi Xu, Prosodic encoding of new topic in Mandarin with Bei Wang, Beijing, China Dates:2004-. Researchers: Yi Xu, Prosody of questions in English and Mandarin with Fang Liu, University of Chicago, USA - To investigate question intonation in Mandarin and English by controlling tone, lexical-stress pattern and focus. The findings so far are consistent with the functional view of intonation, according to which components of intonation are defined and organized by individual communicative functions that are independent of each other but are encoded in parallel. Dates:2003-. Funded by:Collaborative. Researchers: Yi Xu, Quantitative modeling of tone and intonation with Santitham Prom-on and Bundit Thipakorn, King Mongkut’s University of Technology Thonburi, Thailand - To develop a quantitative Target Approximation (qTA) model for simulating F0 contours of speech. Following the articulatory-functional framework of the PENTA model (Xu, 2005), the qTA model simulates the production of tone and intonation as a process of syllable-synchronized sequential target approximation. In the model, tone and intonation are treated as communicative functions that directly specify the parameters of the qTA model. The numerical values of the qTA will be extracted from natural speech via supervised learning. And the quality of the modeling output will be both numerically assessed and perceptually evaluated. Dates:2005-. Funded by:Collaborative. Researchers: Yi Xu, Spoken Language Conversion with Accent Morphing Spoken language conversion is the challenge of using synthesis systems to generate utterances in the voice of a speaker but in a language unknown to the speaker. Previous approaches have been based on voice conversion and voice adaptation technologies applied to the output of a foreign language TTS system. This inevitably reduces the quality and intelligibility of the output, since the source speaker will not be a good source of phonetic material in the new language. Our work contrasts previous work with a new approach that uses two synthesis systems: one in the source speaker's voice, one in the voice of a native speaker of the target language. Audio morphing technology is then exploited to correct the foreign accent of the source speaker, while at the same time trying to maintain his or her identity. In this project we aim to construct a spoken language conversion system using accent morphing and evaluate its performance in terms of intelligibility and speaker identity. Dates:2006-. Researchers: Mark Huckvale, Kayoko Yanagisawa, The size code in the expression of anger and joy in speech with Suthathip Chuenwattanapranithi, King Mongkut’s University of Technology Thonburi, Thailand - To test the “size code” hypothesis for encoding anger and joy in speech. According to the hypothesis, these two emotions are conveyed in speech by exaggerating or understating the body size of the speaker, just as nonhuman animals exaggerate or understate their body size to communicate threat or appeasement. We will conduct acoustic analysis of publicly available emotional speech databases, and synthesize Thai vowels with a 3D articulatory synthesizer using parameter manipulations suggested by the size code hypothesis, and asked Thai listeners to judge the body size and emotion of the speaker. Initial results are in support of the size code hypothesis. Dates:2005-. Funded by:Collaborative. Researchers: Yi Xu, Timing and coordination in speech production To test the hypothesis proposed in Xu (Lingua, in press), Xu & Liu (2006): The onset of the syllable, where consonant, vowel, tone and phonation register all start to approach their respective targets, provides a recurrent time marker with which timing can be controlled by the speaker and tracked by the listener. Dates:2007-. Funded by:Internal. Researchers: Yi Xu, Speech & Hearing Science Projects List of Completed Research Projects
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