Age-related effects on two-tone suppression and consonant perception in noise

Abstract

Two-tone suppression reduces gain in the cochlea nearly instantaneously in a frequency-dependent manner. In speech perception, suppression may enhance spectral contrasts between regions of higher and lower energy. A few previous studies have investigated the effects of aging on suppression and correlations with speech perception in noise, but none have looked at the adaptability of suppression with preceding stimulation. In the present study, estimates of two-tone suppression and consonant perception were measured in younger and older adults. Suppression was measured with short tonal stimuli with and without preceding stimulation. Consonant vowel (CV) stimuli consisted of combinations of the consonants /b, g, d/ and the vowels /ɑ, i, u/ spoken by three male speakers. Broadband noise was filtered to match the long-term average spectrum of the speech stimuli used. CV onset was either 0 or 70 ms after onset of the noise. Participants were asked to identify the consonant by choosing /b/, /g/ or /d/. Percentage correct was calculated for CVs in quiet and in + 5, 0, −5, and −10 dB signal-to-noise ratio conditions. Suppression and adaptability were found to correlate with several aspects of speech perception in noise. Age-related results and implications will be discussed. [Research supported by NIH(NIDCD)F31 DC014395.]