Encoding of rapid amplitude fluctuations by Cochlear-nerve fibres in the guinea-pig.

Responses of cochlear nerve fibres in the guinea-pig were measured to sinusoidally amplitude-modulated tones at fibre characteristic frequency. The modulation depth was +/- 3 dB and the modulation rate was varied between 6.25 and 6400 Hz keeping the mean level of the tone constant. The resultant period histogram (locked to the modulation cycle) was used to determine the depth of modulated neural discharge. The functions showing the variation of discharge modulation with modulation frequency were, in general, low-pass. The cut-off of these functions appears to be primarily determined by the filtering properties of the fibres.