Perception of combined intensity and frequency contours by normal-hearing and hearing-impaired listeners

Abstract

When a speaker utters a consonant-vowel or vowel-consonant syllable, the frequency transitions are critical to identification of the sound. However, an intensity contour is also superimposed on the frequency glides, as the mouth opens or closes. In this study, the interaction of frequency and intensity contours was explored using a frequency glide discrimination task. Offset frequency difference limens (offset DLs) were measured for upward and downward frequency glides in two frequency regions, and with three intensity contours, increasing from silence, decreasing to silence, and steady-state. For both normal-hearing (NH) and hearing-impaired (HI) subjects, larger offset DLs were observed for the high frequency stimuli than for the lower frequencies, and for upward-gliding stimuli than for downward frequency glides. Amplitude contour had little effect on the NH data, but did influence offset DLs for HI subjects. These findings indicate that for these stimuli, the interaction of frequency and amplitude contours plays only a small role in the perception of transition-like glides for NH listeners, but may affect the perception of frequency transitions by HI listeners. [Work supported by NIDCD.]