One of the mysteries in the study of hearing is how we are able to localize sounds accurately in reverberant environments in which the majority of sound energy is from different directions than the true source of sound. The reflected sound is not ignored by the auditory system;it colors the sound image and adds to the loudness and spatial width of the perceived sound. Nevertheless, as a result of the well-known precedence effect, localization is seriously affected only in the most extreme reverberant environments. The goal of our work is to achieve a better understanding of the precedence effect, the processes through which it operates, and its importance in understanding speech in noise. The first of three specific aims will consider how, and under what circumstances, the first wave of sound that strikes the ears controls the perceived direction of the auditory image, even if the remainder of the sound would lead to an ambiguous or different localization.
The second aim i s to characterize the fusion of sources and reflections into a single image that is localized near the original source of sound. These studies will investigate the hypothesis that fusion is enhanced as the listener constructs an internal model the acoustic spatial environment.
The third aim i s to determine how the precedence effect assists listeners in understanding speech in common situations in which multiple conversations occur simultaneously. .The studies will investigate the role of sound localization in understanding speech when the speech signal is degraded in ways relevant to listening with hearing loss, hearing aids and cochlear implants. In this way, the proposed research will help inform decisions that will improve speech recognition by hearing-impaired individuals wearing prostheses. Specifically, this research will determine which cues are critical to preserve and deliver for sound localization when designing or prescribing prosthetic devices.

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
Research Project (R01)
Project #
Application #
Study Section
Auditory System Study Section (AUD)
Program Officer
Donahue, Amy
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Massachusetts Amherst
Schools of Public Health
United States
Zip Code
Morse-Fortier, Charlotte; Parrish, Mary M; Baran, Jane A et al. (2017) The Effects of Musical Training on Speech Detection in the Presence of Informational and Energetic Masking. Trends Hear 21:2331216517739427
Freyman, Richard L; Terpening, Jenna; Costanzi, Angela C et al. (2017) The Effect of Aging and Priming on Same/Different Judgments Between Text and Partially Masked Speech. Ear Hear 38:672-680
Freyman, Richard L; Zurek, Patrick M (2017) Strength of onset and ongoing cues in judgments of lateral position. J Acoust Soc Am 142:206
Helfer, Karen S; Freyman, Richard L (2016) Age equivalence in the benefit of repetition for speech understanding. J Acoust Soc Am 140:EL371
Helfer, Karen S; Merchant, Gabrielle R; Freyman, Richard L (2016) Aging and the effect of target-masker alignment. J Acoust Soc Am 140:3844
Zobel, Benjamin H; Freyman, Richard L; Sanders, Lisa D (2015) Attention is critical for spatial auditory object formation. Atten Percept Psychophys 77:1998-2010
Freyman, Richard L; Morse-Fortier, Charlotte; Griffin, Amanda M (2015) Temporal effects in priming of masked and degraded speech. J Acoust Soc Am 138:1418-27
Helfer, Karen S; Staub, Adrian (2014) Competing speech perception in older and younger adults: behavioral and eye-movement evidence. Ear Hear 35:161-70
Ruggles, Dorea R; Freyman, Richard L; Oxenham, Andrew J (2014) Influence of musical training on understanding voiced and whispered speech in noise. PLoS One 9:e86980
Helfer, Karen S; Mason, Christine R; Marino, Christine (2013) Aging and the perception of temporally interleaved words. Ear Hear 34:160-7

Showing the most recent 10 out of 36 publications