Perception of Spectral Ripples and Amplitude Compressed Speech by Individuals with Cochlear Hearing Loss

Abstract

Spectral ripple discrimination test assesses the frequency resolution of an individual’s auditory system. In this study, spectral ripple discrimination ability was investigated in normal and hearing impaired listeners. The task involved discriminating between two rippled noise stimuli in which the frequency positions of the decibel amplitude-spaced peaks and valleys were interchanged. The ripple spacing was varied adaptively from 1.000 to 11.31 ripple/octave, and the minimum ripple spacing at which a reversal in peak and trough positions could be detected was determined as the spectral ripple discrimination threshold for each listener. Results showed that, the spectral ripple discrimination was best, on average, in normal listeners compared to hearing impaired listeners. SNR loss for compressed speech was greater than that for original speech and also it was found that SNR loss for slow-acting compression was less, indicating good speech intelligibility compared to fast-acting compression in hearing impaired listeners. Results of the study revealed that spectral ripple discrimination method can be reliably used to study individual’s frequency resolution ability and be used to predict SNR loss. Thus the ability to process fine structure information may lead to implications for the choice of compression speed in hearing aids.