Phase-lock of spontaneous oto-acoustic emissions to a cubic difference tone
Pim van Dijk, Hero P. Wit · The Journal of the Acoustical Society of America · 1987
If a single external tone is used to study phase-lock of a spontaneous oto-acoustic emission, it is difficult to separate this tone from the emission signal. Therefore, two tones with frequencies f1 and f2 and levels L1 and L2 were presented to ears having a spontaneous oto-acoustic emission. Here, f1 and f2 produced a 2f1 − f2 distortion product close to (< 50 Hz) the emission frequency f0. Frequency spectra and zero-crossing time trend recordings were obtained for various values of L1, L2,f1, and f2. When the L1 and L2 were sufficiently high, the emission was phase locked to the 2f1 − f2 tone generated in the ear. When L1 and L2 were small, the emission was sustained at f0. At intermediate levels, the emission is not constantly locked to 2f1 − f2, but occasionally jumps to f0. The behavior described above is identical to that of a self-sustained oscillator in the, presence of noise, driven by an external tone [R. L. Stratonovich, Topics in the Theory of Random Noise (Gordon and Breach, New York, 1963), Vol. II, Chap. 9]. [Work supported by Z. W. O.]