Auditory-inspired pitch extraction using a synchrony capture filterbank

Abstract

The question of how harmonic sounds in speech and music produce strong, low pitches at their fundamental frequencies, F0’s, has been of theoretical and practical interest to scientists and engineers for many decades. Currently the best auditory models for F0 pitch, (e.g., Meddis & Hewitt, 1991), are based on bandpass filtering (cochlear mechanics), half-wave rectification and low-pass filtering (hair cell transduction, synaptic transmission), channel autocorrelations (all-order interspike interval distributions) aggregated into a summary autocorrelation, followed by an analysis that determines the most prevalent interspike intervals. As a possible alternative to explicit autocorrelation computations, we propose an alternative model that uses an adaptive Synchrony Capture Filterbank (SCFB) in which channels in a filterbank neighborhood are driven exclusively (captured) by dominant frequency components closest to them. Channel outputs are then adaptively phase aligned with respect to a common time reference to compute a Summary Phase Aligned Function (SPAF), aggregated across all channels, from which F0 can then be easily extracted. Possible relations to brain rhythms and phase-locked loops are discussed. [Work supported by AFSOR FA9550-09-1-0119, Invited to special session about Synchronization in Musical Acoustics and Music Psychology.]