Donna J. Gelnett
Michael J. Nilsson
Sigfrid D. Soli
House Ear Inst., 2100 W. 3rd St., Los Angeles, CA 90057
Binaural directional hearing, the ability of a listener to ``tune out'' noise from one direction and listen to a signal from another direction, improves speech intelligibility in noise. This ability is present in the hearing-impaired individual, but may be reduced as a result of hearing impairment. The present research examined the relationship between aided and unaided directional hearing, and directional hearing capacity---as measured under headphones with simulated head-related transfer functions and idealized amplification. Reception thresholds for sentences (RTSs) were measured with and without spatial separation of the speech and a spectrally matched noise for 25 hearing-impaired binaural hearing aid users. Directional hearing capacity for these individuals often fell within the normal range. Unaided RTSs were elevated 3--6 dB on average over the capacity measures. Aided RTSs were also elevated 2--3 dB over average scores for directional hearing capacity, suggesting that the interaural cues for binaural directional hearing are either inaudible or absent from the hearing aid output. Detailed analyses will be reported with respect to the type of hearing aid, hearing aid transfer function, and degree of hearing loss.