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Researchers in the Department of Physiology, Anatomy and Genetics (DPAG) have found that the auditory system adapts to the changing acoustics of reverberant environments by temporally shifting the inhibitory tuning of cortical neurons to remove reverberation.

Collage of one large room, one smaller and two Cochleagrams
The effects of reverberation on natural sounds. Each panel shows the modelled representation of the same natural sound in the ferret inner ear, known as a “cochleagram”, in a small room with weak reverberation such as an office (left panel), or a large room with strong reverberation such as a church (right panel).

The sounds we hear in almost every environment are reflected by nearby objects, producing many delayed and distorted copies of the original sound, known as reverberation. Our brains are usually able to filter this out, allowing us to recognise the source of each sound regardless of the environment, to the extent that people with normal hearing rarely notice it at all. However, reverberation is known to cause severe difficulties for many people with hearing impairments, and for speech recognition algorithms such as those designed to assist those who cannot hear.

Despite the ubiquity of reverberation, the question of how the brain’s auditory system copes with reverberation has been largely unanswered. Recent research has observed that the effects of room reverberation seem to be partially removed from the neural responses to sounds in the auditory cortex. However, so far it has been largely unknown how the brain could ‘remove’ reverberation in this way.

A new paper from DPAG's King and Walker research groups has demonstrated, for the first time, how the brain may accomplish this ‘reverberation cancellation’. Their data shows that auditory cortical neurons adjust their filtering properties to adapt to changing acoustics of reverberant environments and reduce the effects of reverberation.

Read the full story on the DPAG website