Sound, vision & hearing loss

Science | Health - Cath Harris | 23 Jun 11. The mechanisms used by the brain to distinguish contrasting sounds may be similar to those used to visually pick out a face in the crowd. Scientists at Oxford University's Department of Physiology, Anatomy and Genetics are studying the ways in which sound is represented in the brain and their latest research, published in the journal Neuron , looks at how the brain's nerve cells respond to sounds heard under different conditions. The study, carried out by Neil Rabinowitz, Ben Willmore, Jan Schnupp and Andrew King, shows that neurons in the auditory cortex of the ferret's brain adjust their activity to compensate for the contrast between a sound and its background. Examples in human terms could be situations where the underlying environment is silent or very quiet - such as the countryside at night - or very loud, as in a busy pub or high street. This is known as contrast gain control, a mechanism that our visual systems are thought to use to help focus attention on a particular object. Professor King says: 'There could be a similar mechanism in the auditory system for picking out sounds of interest against a background of other sounds of different frequencies.' The research is contributing to the efforts of Professor King's group to unravel the way the brain processes sound.