Improving speech intelligibility in fluctuating background interference

Abstract

The masking release (MR; i.e., better speech recognition in fluctuating compared to continuous noise backgrounds) that is evident for normal-hearing (NH) listeners is generally reduced or absent in hearing-impaired (HI) listeners. In this study, a signal-processing technique was developed to improve MR in HI listeners and offer insight into the mechanisms influencing the size of MR. This technique compares short-term and long-term estimates of energy, increases the level of short-term segments whose energy is below the average energy, and normalizes the overall energy of the processed signal to be equivalent to that of the original long-term estimate. In consonant-identification tests, HI listeners achieved similar scores for processed and unprocessed stimuli in quiet and in continuous-noise backgrounds, while superior performance was obtained for the processed speech in some of the fluctuating background noises. Thus, the energy-normalized signals led to larger values of MR compared to that obtained with unprocessed signals.