The proposed research has three overall objectives: first, to investigate the acoustic properties which enable listeners with normal hearing to separate speech from competing sounds, including other voices; second, to study the perceptual strategies used by listeners to extract these properties from the composite waveform; and third, to develop and evaluate a model of speech-source segregation. Individuals suffering from hearing impairment of cochlear origin often report difficulties in understanding speech when competing voices are present. Research on the perceptual processes involved in separating speech from other sounds may provide insights into the difficulties faced by hearing-impaired listeners,-and may suggest forms of signal processing to enhance the intelligibility of speech signals corrupted by background noise and thereby improve the design of future signal-processing hearing aids. The experimental component of the project will investigate the role of voice fundamental frequency (f 0) and formant frequencies in the perceptual segregation of competing voices. In one set of experiments, listeners will attend to a mixture of two synthesized """"""""Voices"""""""" and identify what each of them is saying. The contribution to voice separation of f 0 differences, f, changes over time, and formant frequency changes over time will be assessed in terms of the accuracy of identification performance. A second set of experiments will use a matching paradigm to examine the link between pitch perception and voice segregation. A third set will use a vowel-matching task to examine the perceptual consequences of formant overlap, which frequently exists when voices compete. The modeling component of the project involves the further development and evaluation of a computational model of the auditory and perceptual processes underlying the performance of listeners in tasks involving two competing voices (Assmann and Summerfield, 1990). New development& will include the introduction of a sliding time analysis window to accommodate changing f o's and changing formant patterns, and an elaborated segregation procedure which reflects the findings of the perceptual experiments.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
1R29DC001258-01
Application #
3461833
Study Section
Hearing Research Study Section (HAR)
Project Start
1991-07-01
Project End
1996-06-30
Budget Start
1991-07-01
Budget End
1992-06-30
Support Year
1
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Texas-Dallas
Department
Type
Other Domestic Higher Education
DUNS #
City
Richardson
State
TX
Country
United States
Zip Code
75080
Assmann, P F; Paschall, D D (1998) Pitches of concurrent vowels. J Acoust Soc Am 103:1150-60
Assmann, P F (1996) Modeling the perception of concurrent vowels: Role of formant transitions. J Acoust Soc Am 100:1141-52