Susan Dwyer
Univ. of Kansas Med. Ctr.
Peggy B. Nelson
Ctr. for Audit. and Speech Sci., Gallaudet Univ., 800 Florida Ave. NE, Washington, DC 20002
Previous investigations of gap detection by hearing-impaired listeners have yielded results that are inconsistent across listeners and studies. The full effect of stimulus intensity and audibility on hearing-impaired listeners' performance has not been described. This study investigated the effect of intensity on gap detection abilities of normal-hearing listeners and listeners with similar mild to moderate high-frequency hearing impairments. Listeners were required to detect a gap in a high-frequency narrow-band noise over a wide range of intensities above threshold, and to judge the loudness of the signal. Results indicated that at low intensities all listeners showed reduced gap detection ability. As intensity increased, the listeners' performance improved and stabilized at high sensation levels. At these higher intensities, the performance of hearing-impaired listeners was similar to, but still significantly different from that of normals (mean group difference=1 ms). This difference in listeners' performance was found when results were compared in sensation level, sound-pressure level, and loudness. Consistent results across eight hearing-impaired listeners suggested that ensuring full audibility of the stimulus yields more consistent performance. These results suggest that temporal resolution ability is affected by both hearing impairment and by stimulus intensity.