Nl and N2 gross neural action potentials were measured from the round window of the guinea pig cochlea at the onset of the acoustic stimuli. Nl -N2 audiograms were made by means of regulating stimulant intensities in order to produce constant Nl -N2 potentials as criteria for different input tone pip frequencies. The lowest threshold was measured with an input tone pip 15 dB SPL in intensity and 12 KHz in frequency when the animal was in normal physiological condition. The procedure of experimental measurements is explained in detail. This experimental approach is very useful for the investigation of the Cochlear function. Both nonlinear and active functions of the Cochlea can be monitored by Nl -N2 audiograms. Key words : Guinea Pig, Cochlea, Wl and N2 Gross Neural Action Potential, Nl -N2 Audiogram