Auditory Spectral Filtering and Monaural Phase Perception

The fundamental relation of limited auditory frequency resolution to mortar phase perception is studied. Old and new results are discussed for experiments employing sinusoidally amplitude-modulated (AM) carrier tones and quasi-frequency modulated (QFM) carrier tones, which are related by a phase transformation. One experiment concerns AM and QFM modulation thresholds. A second experiment considers the quality differences between AM and QFM. Both experiments show that phase effects disappear for stimulus bandwidths that exceed a value roughly proportional to the critical band at the carrier frequency. The proportionality factor depends upon carrier level and differs greatly between experiments. A unified psycho-physical account is given with a model consisting of a quasilinear bandpass analyzing filter followed by ideal envelope detection, and concluding with either a peak-to-minimum or peak-threshold decision. Parameter values in the model are evaluated from the phase-perception data, and these values support the assumptions that underlie the model. It is shown that the critical-bandlike experimental data do not provide a measure of the commonly conceived critical band. Rather, the critical-band scale merely normalizes the analyzing-filter parameters. This work indicates that the model employed offers wider application.