History of silence affects auditory evoked fields regardless of intervening sounds: a magnetoencephalographic study

The amplitudes of auditory evoked N1 m responses are known to depend on the length of the pre-stimulus silent interval. However, it remains unknown whether pre-penultimate silent intervals affect the auditory evoked responses elicited by test stimuli. In the present study, we investigated the N1 m responses elicited by a train of four successive tones with a silent interval of 1 s subsequent to that with a 0.25-, 0.5-, 2- or 4-s silent interval using magnetoencephalography. The results obtained demonstrated that the N1 m source strength decreased as the pre-penultimate silent interval became shorter. A history of silences had a significant impact on the N1 m source strength. Human brain activity that is modulated by silence history may play an important role in encoding a series of sound streams that include silences, such as speech and music.