Mammalian pitch sensation shaped by the cochlear fluid

Abstract

The perceived pitch of a complex harmonic sound changes if the partials of the sound are frequency-shifted by a fixed amount. Simple mathematical rules that the perceived pitch could be expected to follow ('first pitch-shift') are violated in psychoacoustic experiments ('second pitchshift'). For this, commonly cognitive cortical processes were held responsible. Here, we show that human pitch perception can be reproduced from a minimal, purely biophysical, model of the cochlea, by fully recovering the psychoacoustical pitch-shift data of G.F. Smoorenburg (1970) and related physiological measurements from the cat cochlear nucleus. For this to happen, the cochlear fluid plays a distinguished role.

Auditory Power-Law Activation Avalanches Exhibit a Fundamental Computational Ground State

“…This model reproduces virtually all mesoscopic biophysical cochlear observations ( [16][17][18][19][20]; in particular Supplemental Material of Refs. [16,18,19]). Fundamental for this is that the sections share the dynamical properties of the microscopic amplification-providing outer hair cells [14,21], which is well modeled by a stimulated Hopf process:…”

“…Figure 2 exhibits the activation network from the input of two complex tones (our complex tones always consist of five consecutive harmonics, starting with the fundamental frequency). Activated nodes relate either to a harmonic of a stimulation or to a combination tone of already activated nodes; combination tones have a prominent role in human pitch perception [18,19,28,29]. A 0.65-kHz tone, e.g., is generated as the 2f 1 − f 2 combination tone, with f 1;2 ¼ f2; 3.35g kHz.…”

Modeling cochlear two-tone suppression using a system of nonlinear oscillators with feed-forward coupling

“…Similar models have also been considered in Refs. [15,16]. Figure 1A shows a schematic illustration of the model, a one-dimensional array of nonlinear oscillators with feed-forward coupling.…”

“…It is considered that the cochlea can be modeled as an array of such active oscillators slightly below the onset of spontaneous oscillation, which are coupled mechanically and through the lymphatic fluid with high viscosity in the cochlear duct [8][9][10][11][12][13][14]. Development of biomimetic acoustic sensors that take into account the amplification characteristics of the cochlea has also been attempted [3,[15][16][17].…”

Noise-induced distortion of the mean limit cycle of nonlinear oscillators

“…The dynamics of individual hair cells, as well as the overall mechanical response of the inner ear, have been modeled with various systems of nonlinear differential equations of multiple levels of complexity [15,[28][29][30]. A simple two-dimensional mathematical system exhibiting the supercritical Hopf bifurcation, known as the normal form equation, has been shown to reproduce the main aspects of the auditory response [16][17][18].…”