ASA 126th Meeting Denver 1993 October 4-8

3aPP7. Localization of sound sources in the median sagittal plane by listeners with high-frequency hearing loss.

Timothy J. Vander Velde Brad Rakerd

Dept. of Audiol. and Speech Sci., Michigan State Univ., East Lansing, MI 48824

William Morris Hartmann

Michigan State Univ., East Lansing, MI 48824

Sources in the median sagittal plane are localized on the basis of spectral cues. The elevation of sources toward the front is determined from cues at high frequency (7 kHz and above). The distinction between front, overhead, and back (FOB) potentially involves broadband cues. One therefore expects that individuals with high-frequency hearing loss will fail at elevation tasks, though they might succeed at FOB tasks. Listeners with bilateral sensorineural hearing loss, moderate in the speech range and severe at high frequencies, were given source identification tasks in both elevation (three sources spanning 30 deg) and FOB geometries. The stimuli were white noise bursts, ranging in level from 42 to 90 dB SPL. A control experiment showed that the listeners could successfully identify sources in the left-overhead-right plane. Results for the sagittal plane showed that all listeners performed significantly less well than normal controls. In the FOB task, performance was well above chance, though listeners characteristically lacked either a front sensation or else a back sensation. In the elevation task, performance was, with a few exceptions, near chance for all listeners and all levels. [Work supported by the NIDCD, DC00181.]