We measured auditory steady-state responses (ASSRs) in magnetoencephalogram when an ongoing sinusoidal amplitude-modulated tone is presented to the subject's left ear while bursts of white noise of various intensities were presented to the right ear. Because the power and coherence as functions of the noise intensities differed considerably among subjects, we used their maximum values as test statistics for testing the group data. The results showed a significant enhancement in the phase coherence of ASSRs obtained over the right temporal regions by the presence of white noise of appropriate intensity. The observed SR most likely occurred within the central nervous system. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.