Detection and discrimination of spectral peaks by listeners with moderate to severe hearing losses

Abstract

Summers and Leek (1994) demonstrated that listeners with moderate hearing loss have a reduced ability to identify spectral peaks in broadband stimuli coincident with increased auditory filter bandwidths, but that abilities were presumed sufficient for vowel identification. The current study investigated spectral ripple detection and ripple frequency discrimination with listeners having moderate and severe losses. Stimuli were flat spectrum pure-tone complexes log-spaced over 2-oct bands (1000–4000 Hz and 500–2000 Hz). In one experiment the different signal’s spectrum was multiplied by sinusoidal log-spaced ripples. Ripple frequency was held constant while ripple amplitude adapted. In the second experiment, all signals contained constant-amplitude ripples with ripple frequency adapting. Preliminary results for moderate loss listeners indicate ripple detection thresholds for both 2-oct band stimuli are similar to those previously reported. Comparatively, listeners with flat severe losses have markedly poorer ability to detect spectral peaks, and performed significantly poorer for detecting ripples in the higher-frequency stimuli than in the lower-frequency stimuli. Results suggest that vowel distinctions based on formant discrimination may be difficult for these listeners. Also, deficient consonant identification may be associated with reduced ripple detection ability; the severely hard-of-hearing listener with the largest ripple threshold also had the poorest word identification. [Work supported by NIDCD Grant No. K0800124.]