Effects of center frequency on binaural auditory filter bandwidth in the human brain.

Effects of center frequency on the binaural auditory filter in the human auditory cortex were examined using auditory-evoked magnetic fields. Two tones with different frequency separations, which were presented dichotically to the left and right ears, were used as the sound stimuli. Eight normal-hearing participants took part in the study. The amplitudes of the N1m components of auditory-evoked magnetic fields were approximately constant when the frequency separation was less than 10-20% of the center frequency; however, the N1m amplitudes increased with increasing frequency separation when the frequency separation was greater than 10-20% of the center frequency. This indicates that binaural auditory filter bandwidth is approximately 10-20% of the center frequency.