Harmonic Cancellation - a Fundamental of Auditory Scene Analysis

Abstract

This paper reviews the hypothesis of {\em harmonic cancellation}\ according to which an interfering sound is suppressed or canceled on the basis of its harmonicity (or periodicity in the time domain). It defines the concept, discusses theoretical arguments in its favor, and reviews experimental results that support it, or not. If correct, the hypothesis likely draws on time domain processing of temporally-accurate neural representations within the brainstem, as required also by the classic Equalization-Cancellation (EC) model of binaural unmasking. It predicts that a target sound corrupted by interference will be easier to hear if the interference is harmonic than inharmonic, all else being equal. This prediction is borne out in a number of behavioral studies, but not all. The paper reviews those results, with the aim to understand the inconsistencies and come up with a reliable conclusion for, or against, the hypothesis of harmonic cancellation within the auditory system.

Why is the perceptual octave stretched? An account based on mismatched time constants within the auditory brainstem

“…An analogous circuit can approximate the harmonic cancellation filter (de Cheveigné, 2021). A neuron is contacted by an excitatory and an inhibitory synapse, one fed from a direct pathway, the other via a delay (Fig.…”

Mammalian octopus cells are direction selective to frequency sweeps by excitatory synaptic sequence detection

“…We surmise that this sensitivity provides a basic display mechanism which can be recruited for a variety of perceptual tasks, which likely differ between species. For example, temporal interactions between harmonics of different sound sources, e.g., different speakers, have repeatedly been proposed as a mechanism to segregate such sounds (68)(69)(70)(71)(72)(73)(74). Our findings suggest that octopus cells are very sensitive to such interactions.…”

Why is the perceptual octave stretched? An account based on mismatched time constants within the auditory brainstem

“…The cancellation filter (Eq. 3) is one way to implement harmonic cancellation, a hypothetical process according to which the auditory system exploits the harmonic structure of a background sound to better hear a weak target (de Cheveigné, 2021). This is applicable to detection of a mistuned component within a harmonic complex (Moore et al, 1985;Hartmann et al, 1990), as cancelling the harmonic complex should make the mistuned component more salient, for example making its pitch easier to match (Hartmann and Doty, 1996).…”

“…Mistuning from a harmonic octave (simultaneous tones), akin to detection of mistuning of a partial from a harmonic series (Moore et al, 1986;Hartmann et al, 1990), could be detected by a mechanism such as harmonic cancellation (de Cheveigné, 2021). This requires no memory.…”