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Research
My NIH-supported research, jointly conducted with Bruce Gerratt, PhD, focuses on the perception (and secondarily on the production) of normal and pathological voice. Voice quality is a primary means by which humans signal their identity, internal state, and intentions to others, and voice disorders can have devastating personal and professional consequences, creating an undesirable personal image and making vocal communication difficult or impossible. However, despite the importance of voice perception and large literatures in disciplines ranging from music to medicine, little progress has been made in understanding how listeners perceive voices. In fact, the modern history of voice research may be viewed as a series of efforts to circumvent the problem of measuring quality by substituting “objective” measures of acoustics, physiological functions, or airflow. Unfortunately, objective measures of quality are meaningless unless they are validated against perceptual measures. Thus, perception of voice remains of central importance even in efforts to eliminate perceptual measures.
Our research attempts to develop models of voice perception and speaker recognition. Without such models, the goal of understanding how listeners perceive voices will not be achieved. Initial studies in the laboratory sought to specify the sources of variability in listeners’ ratings of vocal quality. More recently, studies have focused on developing reliable, valid methods to measure perceived vocal quality, by controlling the factors underlying response variability. We have devised a new, theoretically-motivated method of assessing quality – listener-mediated analysis-resynthesis—in which listeners explicitly compare synthetic and natural voice samples, and change speech synthesizer parameters to create acceptable auditory matches to voice stimuli. This method is designed to replace usable internal standards for qualities like breathiness and roughness with externally-presented stimuli. Initial results indicate that this technique does control the major hypothetical sources of disagreement in rating scale judgments.
A reliable and valid method of measuring what listeners hear is an essential component of a common theoretical framework that links together physiology, aerodynamics, acoustics, and perception, to explain how tissue movement finally results in the perception of speech sounds. However, voice production, perception, and acoustics in the past have been studied as nearly independent disciplines, with little cross-fertilization of ideas and virtually no theory to link levels of description. A unified approach to the study of voice could have many potential benefits, including theoretically motivating surgeries to improved voice quality, allowing prediction of post-surgical voice quality given a patient’s particular findings, motivating objective measures of voice, specifying which aspects of a voice are essential to its identification, and so on. Development of such ah theory (in collaboration with other faculty members in Head and Neck Surgery, Engineering, and Linguistics) is the ultimate goal of this ongoing research.
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Teaching
In addition to teaching duties in Head and Neck Surgery, I teach Communication Studies 197J, “Voice and Its Perception” http://www.sscnet.ucla.edu/01W/comm197j-2/ In this class, students learn how the human voice is produced, how it can vary, how listeners gather information about speakers from voices, and how voice information is manipulated in the media (for example, in radio advertising).
Education: PhD (Linguistics)
Institution: University of Chicago
Year: 1987
Postdoctoral Education
Institution: UCLA
Department: Division of Head/Neck Surgery
Year: 1988 - 1990
Research Interests
- Perception, production, and acoustics of the human voice
- Perception of personal attributes from voice
- Linguistic uses of voice quality
- Voice synthesis
Clinical Interests
- Clinical evaluation of voice quality
Honors and Awards
- Principal investigator, NIH NIDCD Individual Research Grant
“Toward standardizing perceptual voice quality measures” (DC01797), 2000-2005
Academic/Teaching Appointments
- Division of Head and Neck Surgery, UCLA
- Department of Communication Studies, UCLA
Titles
Memberships in Scholarly or Professional Societies
- Acoustical Society of America
- American Association for the Advancement of Science
- American Speech-Language-Hearing Association
- International Phonetic Association
National Elected Office Organizations
- Speech Communication Technical Committee
- Acoustical Society of America
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