Delayed evoked oto-acoustic emissions and their suppression by Gaussian-shaped pressure impulses.

The sound pressure of delayed evoked oto-acoustic emissions was measured as a function of the sound pressure of the stimulating sound impulse. They are directly proportional for sensation levels of the stimuli lower than about 20 dB; above that level, the emission saturates. Spontaneous emissions lying in the same frequency range as evoked emissions seem to influence this simple relation. Within the linear range, delayed emissions superimpose linearly even throughout long lasting delayed emissions. Short test tone bursts were used as test sound, to produce masking-period patterns, and as stimulus, to produce suppression-period patterns, respectively, while low-frequency Gaussian-shaped pressure impulses served as masker and as suppressor. The very close relation of the two patterns is indicated by their mirrored forms. This is considered directly relevant to the phenomenon of masking.