ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3pPP10. Sound localization in the median sagittal plane by hearing impaired listeners.

Brad Rakerd

Timothy J. Vander Velde

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

William Morris Hartmann

Michigan State Univ., East Lansing, MI 48824

Previously, it was reported that listeners with substantial high-frequency hearing loss have difficulty localizing sounds in the median sagittal plane [Vander Velde et al., 1812(A) (1993)]. When asked to localize broadband noise, they performed near chance level on an elevation task and somewhat better, but far below normal, on a task that required that they distinguish between sources to the front, overhead, and rear. In the present study, these experiments were repeated with new subjects (n=16), and with the following variations, each introduced to encourage improved performance. (1) Low-frequency components of the noise stimulus were filtered out to preclude the masking of more informative high-frequency components. (2) The difficulty level of the elevation task was eased. (3) Subjects were tested while wearing their hearing aids. Each of these changes helped a few individuals, typically in small ways, but none produced statistically significant improvement for the group overall (p>0.05). Together, these results point up a significant localization problem for individuals with high-frequency hearing loss of the sort that commonly accompanies aging. The results also support the theory that spectral cues are of the greatest importance for median plane localization. [Work supported by NIDCD.]