Anomalous auditory filter bandwidth derived from direct masking of complex signals

Psychoacoustical thresholds were determined for complex signals (triangular spectral envelope and 2000-Hz center frequency) masked by broadband noise. Variation of the fundamental frequency and of the phase relation between the components had no influence on the masked thresholds, although the temporal envelopes of the complexes were completely different. The bandwidth of the signals was varied by changing the slope of the spectral envelopes. From the dependence of the masked threshold on signal bandwidth the auditory filter bandwidth was estimated to be about 100 Hz at 2000 Hz. Masked thresholds determined for complexes with flat spectral envelope resulted in the same auditory filter bandwidth. These values are extremely narrow compared to the value of about 320 Hz often observed in other measures. It is suggested that the masked thresholds are influenced by temporal interactions.