How pitch is perceived is not clear yet. The theory suggested here is according to an old idea of undertones. When a complex sound with a harmonic overtone strucutre enters the ear, at each bark band on the human cochlear where the sound has partials spikes appear. They fire regularly with the periodicity of the partials frequency. Still the human ear is not always able to follow high frequencies with the same speed as the sound repeats. Therefore drop-outs appear, where only each second, third, fourth, etc. time a spike is released. These new periodicities between spikes are undertones of the partial. As all partials have the same undertone in common, namely the fundamental frequency, at all bark bands with energy this fundamental periodicity will appear. Therefore the fundamental periodicity is much more prominently present in the neural nerve leaving the cochear compard to all other partials. This might explain pitch perception as well as the salience of pitch over timbre.

Spike periodicities of a sound consisting of two complex tones with fundamental frequencies of 400 Hz and 600 Hz. They have a residual pitch at 200 Hz. This appear over a large range of bark bands rather than at just at the 200 Hz bark band.

Spike periodicities of a classical guitar tone. The fundamental pitch at 208 Hz is present at nearly all bark bands. A second periodicity appears at about 100 Hz which is the Helmholtz resonance of the guitar and inharmonic to the tone. Also this pitch appears over very many bark bands.


Related publications

Bader, R.: Pitch and timbre discrimination at wave-to-spike transition in the cochlea. arXiv:submit/2066467 [q-bio.NC] 12 Nov 2017