'Brain plays role in hearing difficulties'

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The Independent Online

Struggling to hear someone properly mid-conversation during a noisy party or gathering may be something most of us have experienced at one time or another.

But a person's brain rather than their ear could be to blame for the inability to "zoom in" on an individual you want to hear - the so-called "cocktail party" problem, new research suggested today.

The study being carried out by Deafness Research UK scientists at the University College London Ear Institute intimated the brain appears to play a greater role than was previously thought in the auditory process.

It is hoped the research, looking at the brain's ability to focus its listening attention on a single speaker amid a mixture of background chatter, but at the same time immediately respond if someone calls our name, will benefit the deaf and hard of hearing.

Particularly those with cochlear implants or "bionic ears" and hearing aids, which traditionally struggle in noisy environments.

Vivienne Michael, chief executive of Deafness Research UK, said: "Scientists are particularly interested in how the central auditory system is able to cope with noisy environments; a major challenge for hearing research over the next decade will be to improve the performance of cochlear implant devices.

"We are only just beginning to appreciate the role the brain and this research gives us hope for improving not just the performance of implants and hearing aids, but the lives of people with hearing disabilities everywhere."

The UCL team is using a variety of techniques to investigate the issue, including in vivo and in vitro brain recordings, psychophysics, computer modelling and human neurophysiology, using electroencephalogram (EEG) and magnetic resonance imaging (MRI).

Research has shown it is particularly those with only one functional ear who are more disturbed by interfering noise.

It is believed the auditory system performs a cross-correlation between the signals coming from each ear and that the brain is capable of analysing the pattern to determine the signal from the desired sound source.

The brain has been described as a radio, selecting which channel we should pay attention to from the many it receives.

It may also have its own mechanism for selection, depending on the importance of the sound stimulus, for example a sudden warning.

Ms Michael added: "Implant users struggle to pick up speech in noisy environments such as pubs and city streets. Future research in this field should aim to understand how to match the electronic signals of a cochlear implant with the brain's requirements for listening in noise."