Abstract:

By processing sounds with combinations of multiband expansion (MBE) and spectral smearing (SS), listeners with normal hearing can experience the elevated thresholds, abnormal growth of loudness, and reduced frequency selectivity similar to those of listeners with sensorineural hearing impairments. The effects of simulations of flat 40-dB losses produced by such combinations on masking patterns and loudness summation, and of simulations of a more severe loss on speech perception in noise, were studied. Both MBE and SS reduce frequency selectivity as measured by masking patterns for tones produced by narrow-band noise, and both broaden forward-masked tuning curves for tones. However, for equally loud probe tones, MBE elevates the tips of psychoacoustic tuning curves much more than SS. As measured by loudness balances between narrow-band and wideband noises, MBE reduces loudness summation much more than SS. The effects of MBE and SS simulations of a severe hearing loss on consonant identification in speech-shaped noise depend on the SNR, with MBE more detrimental at high SNR and SS more detrimental at low SNR. MBE tends to degrade reception of cues for voicing; SS, cues for place of articulation; both degrade cues for manner of articulation. [Work supported by NIH.]