Information Processing in the Cochlea

Precisely defined, informationally relevant, four-dimensional elementary signals or wave packets were used in an investigation of the cochlear microphonic potential (CM) and the summating potential (SP). The acoustical signals are denned by the bounding conditions: Δf Δt = f ₀ t ₀ = 1/2, where Δf is signal bandwidth; Δt is signal duration; f ₀ is signal midfrequency; and t ₀ is signal midperiod. Both potentials elicited by such signals jointly reflect (i) a constant wave (temporal) representation of the constant relations of the elementary signal and (ii) in amplitude, a spatially distributed frequency of the elementary signal and (ii) in amplitude, a spatially distributed frequency representation of the elementary signal. This conclusion is based on recordings made beyond the point of maximum frequency response and which were elicited by signals of high intensity.

The temporal constancy of the CM and SP waveshape elicited by high intensity elementary signals of differing f ₀'s indicates the existence of a frequency dependent temporal delay line. There occurred no spatial distribution of the CM frequencies corresponding to the Δf components, i.e., the shape of the elementary signal was preserved in all turns, indicating that the f ₀ and Δf components of acoustical signals are registered differently in the cochlea. The negative SP also reflects a spatial distribution of frequencies (f ₀) and temporal constancy of waveshape. For a complete understanding of cochlear potentials, a four parameter analysis of acoustical signals is required.