Two-Tone Interactions in a Nonlinear Model of the Basilar Membrane

Hiroyasu SAKAMOTO, Yasuyuki ISO

Summary :

A nonlinear electric circuit model of the whole length basilar membrane (BM) of the human is constructed. It is of transmission analogue type. Nonlinearity is introduced into its loss factors, using resistors and Ge diodes. By observing the membrane velocity of the model, we examine: (i) response to combination tones (CT) with two primary tones of frequency f_L, f_H and level L_L, L_H (f_Lf_H), (ii) 2f_Lf_H CT cancellation characteristics, (iii) two-tone wuppression and (iv) other responses. Suppressed tone has frequency f₁(characteristic frequency (CF) of given section) and level L₁, and suppressor tone has frequency f₂ and level L₂. Distribution of 2f_Lf_H CT component shows that at some sections it cominates the primaries in amplitude, while 2f_Hf_L component is very much smaller all along the model. The 2f_Lf_H CT distribution patterns in the model, when it is cancelled, seem to indicate good correspondence with the psychophysical cancellation. Three CT cansellation characteristics (L_LL_H varied, L_L varied, f_H varied) show good agreement with psychophysical experiments, including the nonmonotonic behavior of the CT. It seems to be possible to have more agreement by using sharper tuning property and stronger nonlinearity. For frequency f₁f₂, average value of BM velocity shows two-tone suppression, but for f₂f₁, it shows a little suppression. It will be worthwhile to consider other variables, such as BM displacement or acceleration, as model output.

• Publication: IEICE TRANSACTIONS on transactions Vol.E65-E No.1 pp.51-58
• Publication Date: 1982/01/25
• Type of Manuscript: PAPER
• Category: Acoustics

Authors

Hiroyasu SAKAMOTO
Yasuyuki ISO

Keyword