Although reseatchers have known about the phenomenon of 'inattentional deafness,' the exact reasons behind it were not known. A team of researchers from University College London conducted a study on how concentrating on a visual task renders people temporarily deaf to the surrounding sounds. They selected a group of subjects who were exposed to a demanding visual task. Simultaneously, the subjects were also exposed to sounds that were clearly audible. However, the subjects were not able to hear them. Their brain activity, which was observed in real-time using MEG (magnetoencephalography), indicated that "people were not only ignoring or filtering out the sounds, they were not actually hearing them in the first place," according to study co-author Dr Maria Chait (UCL Ear Institute). This indicates that the sensory perception of the brain reduces under the load of visual stimuli.
Read more in Science Daily.