Multiple echoes in stimulated oto-acoustic emissions were investigated in 11 normal hearing ears. The stimulus sounds were tone bursts at five frequencies between 1.0kHz and 4.0kHz. Acoustic responses were averaged 500 times with the analysis time of 30ms. The incidence of multiple echoes was highest at 1.5kHz. The number of echoes was also largest at 1.5kHz. The mean pseudothreshold of the first echo was lowest at 2.0kHz and was highest at 4.0kHz. The mean latency of the first echo at the pseudothreshold level was almost the same at five stimulus frequencies, but that of the second echo shortened as the stimulus frequency increased.
