Spectral modulation transfer function and vowel identification.

Abstract

Psychophysical and physiological studies have demonstrated selectivity for spectral modulation frequency in the auditory system, suggesting that auditory perception of complex spectra might be based on spectral modulation channels. However, an early study [Liu and Eddins (2008)] reported that vowel identification was significantly reduced by filtering in spectral modulation frequency domain, although there was no significant correlation between spectral modulation detection thresholds and vowel identification. The latter result may have been due to the small number of listeners (n = 5) in the previous study. Using a larger number of listeners, the present study measured spectral modulation transfer functions and vowel identification performance with and without spectral modulation filtering in 11 normal-hearing listeners. Vowel identification performance was significantly correlated with spectral modulation detection thresholds at 0.5 cyc/oct (i.e., higher spectral modulation detection thresholds associated with poorer vowel identification scores). In addition, average spectral modulation detection thresholds were significantly correlated with the change in vowel identification associated with filtering in the spectral modulation domain. Both of these results highlight the relation between the perception of sinusoidal spectral modulation and vowel identification.