Neuromagnetic and neuroelectric oscillatory responses to acoustic stimulation with broadband noise

We investigated event-related oscillatory responses to acoustic stimulation with EEG and MEG measurements of brain function. EEG and MEG measurements were obtained from healthy adults presented with 500 ms segments of broadband noise presented to both ears via insert earphones. The results showed that auditory stimulation resulted in a reduction in beta band activity within 200 to 400 ms after stimulus onset. The magnitude of this effect was markedly larger when listeners actively attended to sounds than when they ignored them. These results support the conclusion that beta-band oscillations are directly influenced by activation of auditory cortex with acoustic stimulation. However these responses are also strongly modulated by attentional and/or motoric factors related to the auditory task.