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.]