Fundamental frequency discrimination and harmonic resolvability in sensorineural hearing impariment

Abstract

Sensorineural hearing loss (SNHL) often results in impaired fundamental frequency (F0) processing. Three experiments tested the hypothesis that this deficit is related to a loss of frequency selectivity, which may result in fewer peripherally resolved harmonics. F0 difference limens (F0DLs) were measured as a function of F0 for bandpass filtered sine- and random-phase harmonic complexes in listeners with mild-to-moderate SNHL. All listeners showed a transition between small (good) F0DLs at high F0s and large (poor) F0DLs at low F0s, although the transition point varied across subjects. Two measures that are thought to reflect frequency selectivity generally corresponded to the F0DL transition point: the maximum F0 for which F0DLs were phase-dependent, and the minimum modulation frequency required to discriminate amplitude modulation from quasi-frequency modulation. These results provide some support for the idea that the F0-processing deficit associated with SNHL is related to poor frequency selectivity. However, contrary to our hypothesis, poor correspondence was observed between the F0DL transition point and auditory filter bandwidths estimated using the notched-noise method in the same subjects. This suggests a possible discrepancy between traditional spectral-masking estimates of frequency selectivity and estimates based on temporal interactions between unresolved components. [Work supported by NIH grants R01DC05216 and 5T32DC00038.]