Detection of frequency modulation by normally hearing and severely‐to‐profoundly hearing‐impaired listeners

Abstract

Listeners with a severe to profound hearing loss often perceive changes in loudness when the frequency of a stimulus is changed. As a result, researchers who have studied frequency discrimination in impaired listeners may have underestimated the extent of the frequency impairment. In this study, we compare normal and impaired listeners in three frequency modulation detection experiments, in which the amplitudes of the test signals were either fixed, sinusoidally modulated at a constant rate of 3 Hz, or randomly modulated at rates of 3 Hz and below. Results for listeners with normal hearing showed that modulation of signal amplitude yielded Δ FMs that were 2–3 times larger than those obtained with fixed amplitude. Results for one impaired listener tested thus far show abnormally large Δ FMs for all conditions, and, in addition, that Δ FMs obtained with random amplitude modulation are as much as 45 times larger than those found for listeners with normal hearing. [Work supported by NIH.]