Interrupted speech perception: The effects of hearing sensitivity and frequency resolution

Jin & Nelson (2006) found that although amplified speech recognition performance of hearing-impaired (HI) listeners was equal to that of normal-hearing (NH) listeners in quiet and in steady noise, nevertheless HI listeners' performance was significantly poorer in modulated noise. As a follow-up, the current study investigated whether three factors, auditory integration, low-mid frequency audibility and auditory filter bandwidths, might contribute to reduced sentence recognition of HI listeners in the presence of modulated interference. Three findings emerged. First, sentence recognition in modulated noise found in Jin & Nelson (2006) was highly correlated with perception of sentences interrupted by silent gaps. This suggests that understanding speech interrupted by either noise or silent gaps require similar perceptual integration of speech fragments available either in the dips of a gated noise or across silent gaps of an interrupted speech signal. Second, those listeners with greatest hearing losses in the low frequencies were poorest at understanding interrupted sentences. Third, low-to mid-frequency hearing thresholds accounted for most of the variability in Masking Release (MR) for HI listeners. As suggested by Oxenham and his colleagues (2003 and 2009), low-frequency information within speech plays an important role in the perceptual segregation of speech from competing background noise.