Five normal hearing adults were examined for power spectral analysis of AER to 1000-Hz pure tone. Major frequency components of responses to stimuli at 50 dB hearing level exist at 1 to 14 c/s. The power spectra of responses to stimuli at 10 dB hearing level are greater than those of the SBA in the frequency components between 3 and 9 c/s; furthermore, the total power of 3 to 9 c/s indicates a clear difference between the 2. Incidentally, at 512-msec analysis time, the total power of 3 to 9 c/s of the AER are significantly greater than that at 1024-msec analysis time, whereas those of the SBA show little discrepancy at the 2; thus at 512-msec analysis time, the total power of 4 to 9 c/s yields a clear difference between the AER and the SBA responses averaged over 50 stimuli even at 10 dB hearing level.