In a typical room, our ears receive not only the original source of sound, but numerous reflections off of surfaces in the room. Fortunately, through the precedence effect we are able to fuse a sound source and its reflections into a single image and locate that image near the original source of sound. The overall goal of the proposed research is to achieve a better understanding of the precedence effect and its importance in understanding speech in the presence of interfering noise or other speech. The primary assumption is that there are two types of masking of speech: (1) traditional energetic masking, and (2) informational masking, in which it is difficult for the listener to separate out the pattern of the target speech within a fluctuating pattern of interference. In non-reflective conditions, the horizontal separation of target and masking sources releases energetic masking, mostly because the head shadows the masker at one ear and because the brain compares the differences in inputs to the two ears. Unfortunately, this type of masking release is dramatically reduced by the reflections in a real room. The hypothesis tested in this research is that because the precedence effect preserves the perceived spatial distinctions between target and masker even in reverberation, release from informational masking is not reduced by room reflections. The studies will investigate the nature of informational masking and how the precedence effect and binaural hearing in general contribute to overcoming this type of masking. The study of binaural hearing is particularly important because many people with bilateral hearing impairment become effectively monaural listeners when they only wear one hearing aid. The results of these studies may well show how important it is to be able preserve binaural hearing and sound localization when prescribing auditory prostheses. The studies will also investigate the phenomena and mechanisms of the precedence effect on a more basic level, adding to our overall understanding of sound perception in typical reverberant spaces.

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
Research Project (R01)
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Special Emphasis Panel (ZRG1 (01))
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Donahue, Amy
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University of Massachusetts Amherst
Schools of Allied Health Profes
United States
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Freyman, Richard L; Morse-Fortier, Charlotte; Griffin, Amanda M et al. (2018) Can monaural temporal masking explain the ongoing precedence effect? J Acoust Soc Am 143:EL133
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
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
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

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