Brain complexity: directional hearing (Introduction)

by David Turell , Tuesday, May 12, 2015, 19:15 (3483 days ago) @ David Turell

Discriminating sounds and direction, especially thru noise:-http://www.sciencedaily.com/releases/2015/05/150512124134.htm-"Our hearing is so sensitive that we can hear a pin drop and that's because of the 'cochlear amplifier' in our inner ear. This stems from outer hair cells in the cochlea which amplify sound vibrations."-"'When sound intensity increases, the olivocochlear reflex turns down the 'cochlear amplifier' to dynamically balance the input of each ear for optimal hearing, sound localisation and to protect hearing."-"The study found that the cochlear's outer hair cells, which amplify sound vibrations, also provide the sensory signal to the brain for dynamic feedback control of this sound amplification, via a small group of auditory nerve fibres of previously unknown function.-"In mice lacking the sensory fibre connection to the cochlear outer hair cells, loud sound presented to one ear had no effect on hearing sensitivity in the other ear. In normal control mice this produced an almost instant suppression of hearing.-"Similarly, the olivocochlear reflex normally causes a rapid reduction in hearing in the ear receiving an increase in sound. This hearing adaptation was also absent in the mice lacking the sensory fibre connection."