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Why looking at the lips helps understand what people are saying?

Have you been in a situation when you are trying to listen to what someone is saying, but you cannot understand a word because the environment is just too noisy? Maybe it was someone‘s birthday party, maybe just a night out in a club, but that is still very annoying. Looking directly at the lips helps, but why? Is that our conscious effort to read the movement of the lips? Scientists from UCL investigated this question.

Looking at the lips of the person you want to hear may amplify the sound in your brain, making it easier to understand the words even in a very noisy environment. Image credit: Gabriel S. Delgado C. via Wikimedia(CC BY 2.0)

Scientists say that it is actually our brain trick. When the sound that we are hearing is matching what we are seeing our auditory cortex in the brain increases the relevant sound. In other words, what we are looking at determines which sounds our brain focuses on. It is not a conscious effort, but it could potentially help people with hearing disability. People with hearing aids or cochlear implants struggle to understand words in noisy environment, but this simple trick could help them a little bit.

Interestingly, scientists used ferrets as animal models for this study. Scientists presented ferrets with some auditory streams and a visual stimulus in a shape of a light. When one of the streams increased together with increasing intensity of the light, scientists noticed that the auditory cortex in the brain lit up with activity. Another study done in 2015 revealed similar effect in humans. And it all goes to show that our natural desire to look at someone’s lips when they are speaking is not just because we developed a skill of reading lips. It is actually useful on another level – it is helping our brain to decide which sounds should be amplified. It is a good trick to remember when you are somewhere noisy.

It is really an interesting phenomenon, showing how our sight and hearing can be directly linked. Dr Jennifer Bizley, lead author of the study, said: “While the auditory cortex is focused on processing sounds, roughly a quarter of its neurons respond to light – we helped discover that a decade ago, and we’ve been trying to figure out why that’s the case ever since”. And not scientists will try seeing how this could help developing new training strategies for people with hearing disability. Also, in the future it could lead to advanced hearing aid and cochlear implants that could detect what people are looking at.

However, that will still take some time. But it is something people should remember – our brain amplifies the sound of the source we are looking at.

 

Source: UCL

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