Phase relationships and amplitude envelopes in auditory perception

The firing rate of an inner hair cell depends on the amplitude envelope in the associated critical band. Phase relationships between clusters of sinusoids in a critical band affect this envelope. This means that sounds with identical magnitude spectra can result in different firing patterns. This may explain why a pulse train, modeled as a sum of equal amplitude cosines, sounds different than a sum of equal amplitude sinusoids with random initial phase. We demonstrate the effect on firing rate by using a time-domain digital cochlear model. We speculate about other psychoacoustic consequences of phase relationships and amplitude envelopes and their effect on firing rates.