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Second Biennial Hearing Aid Research and Development Conference

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September 22-24, 1997
National Institutes of Health
Bethesda, Maryland



Speech Recognition in Listeners with Impaired Hearing:
Effects of Listening Paradigm

Joan M. Besing and Janet Koehnke, Speech Pathology & Audiology, University of South Alabama, Mobile, Alabama, Kim S. Abouchacra and Tuyen V. Tran, U.S. Army Research Laboratory, APG, Maryland

It is well known that in everyday listening situations, binaural information enhances the ability of individuals with normal hearing to understand speech messages in multitalker environments. However, it is not clear whether individuals with impaired hearing can use this binaural information to improve speech recognition in such environments. Also, for developing virtual auditory tests incorporating multitalker environments, the importance of preserving characteristics of the natural listening environment is not clear.

The purpose of this study was to assess the ability of listeners with impaired hearing (IH) and listeners with normal hearing (NH) to monitor target (T) messages in the presence of synchronous competing (C) messages in four modes: (1) with the T- and C-messages presented diotically through earphones, (2) with the T- and C-messages presented dichotically through earphones, (3) with the T- and C-messages presented through loudspeakers at ±45º and ±135º with the subject seated in the room, and (4) with the environment simulated to create virtual sources at ±45º and ±135º azimuth under earphones. Fourteen subjects with normal hearing and 12 subjects with impaired hearing listened to messages selected from four lists of 2034 10-syllable sentences. In each presentation mode, the T-message was presented 40 times to the subject in the presence of 0, 1, 2, and 3 C-messages; subjects recorded the T-messages.

Overall results demonstrate that the ability to understand the T-messages decreases as the number of C-messages increases for both subject groups. Speech recognition is poorer for the listeners with IH in all four modes than for the listeners with NH. Performance decreases more rapidly with increasing number of C-messages for the IH listeners than the NH listeners.

[Work supported by the ARL.]

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