Nonlinear mechanical behaviour of the basilar membrane in the basal turn of the guinea pig cochlea.

A capacitance probe is used to measure the vibrational displacement of the basilar membrane in the basal turn of the guinea pig. Nonlinear behaviour is exhibited in the region of the mechanical cut-off frequency similar to that previously described only for the squirrel monkey. The degree of nonlinearity appears to be directly correlated with the single unit threshold as reflected in the N1 action potential. Loss of neural sensitivity indicates loss of nonlinear behaviour in the mechanics which is undetectable shortly after death.