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Hearing management

Updated 06 December 2017

What you see is what you hear

Understanding what a friend is saying in the hubbub of a noisy party can present a challenge – unless you can see the friend's face.

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New research from Baylor College of Medicine in Houston and the City College of New York shows that the visual information you absorb when you see can improve your understanding of the spoken words by as much as six-fold.

Your brain uses the visual information derived from the person's face and lip movements to help you interpret what you hear, and this benefit increases when the sound quality rises to moderately noisy, said Dr Wei Ji Ma, assistant professor of neuroscience at BCM and the report's lead author. The report appeared in the open access journal PLoS ONE.

Everyone lip-reads
"Most people with normal hearing lip-read very well, even though they don't think so," said Ma. "At certain noise levels, lip-reading can increase word recognition performance from 10% to 60% correct."

However, when the environment is very noisy or when the voice you are trying to understand is very faint, lip-reading is difficult.

"We find that a minimum sound level is needed for lip-reading to be most effective," said Ma.

How the brain integrates stimuli
This research is the first to study word recognition in a natural setting, where people report freely what they believe is being said. Previous experiments only used limited lists of words for people to choose from.

The lip-reading data help scientists understand how the brain integrates two different kinds of stimuli to come to a conclusion.

Ma and his colleagues constructed a mathematical model that allowed them to predict how successful a person will be at integrating the visual and auditory information.

People actually combine the two stimuli close to optimally, Ma said. What they perceive depends on the reliability of the stimuli.

"Suppose you are a detective," he said. "You have two witnesses to a crime. One is very precise and believable. The other one is not as believable. You take information from both and weigh the believability of each in your determination of what happened."

In a way, lip-reading involves the same kind of integration of information in the brain, he said.

Integration valuable
In experiments, videos of individuals were shown in which a person said a word. If the person is presented normally, the visual information provides a great benefit when it is integrated with the auditory information, especially when there is moderate background noise. Surprisingly, if the person is just a "cartoon" that does not truly mouth the word, then the visual information is still helpful, though not as much.

In another study, the person mouths one word but the audio projects another, and often the brain integrates the two stimuli into a totally different perceived word.

"The mathematical model can predict how often the person will understand the word correctly in all these contexts," Ma said.

(EurekAlert!, March 2009)

Read more:
Many benefits of sign language

 

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Dr Kara Hoffman graduated from UCT in 2004, thereafter she completed her year of community service in Durban. In 2010 she completed her Masters Degree in Paediatric Aural Rehabilitation from UKZN. In 2016, she became a Doctor of Audiology through the University of Arizona (ATSU). Dr Hoffman and her partner Lauren Thompson opened a fully diagnostic audiology practice called Thompson & Hoffman Audiology Inc. In 2011 with world-class technology and equipment to be able to offer the broad public all hearing-related services including hearing testing for adults and babies, vestibular (balance) assessments and rehabilitation, industrial audiology, hearing devices, central auditory processing assessments for school-aged children, school screening, neonatal hearing screening programmes at Alberlito and Parklands Hospital, cochlear implants and other implantable devices, medicolegal assessments and advanced electroacoustic assessments of hearing. Thompson and Hoffman Audiology Inc. are based at Alberlito Hospital in Ballito, St Augustines Hospital in Durban and at 345 Essenwood Road, Musgrave. The practices are all wheelchair friendly. There are three audiologists that practice from Thompson & Hoffman – including Dr Kara Hoffman, Lauren Thompson & Minette Lister. The practice boasts professional, highly qualified, and extensive diagnostic services where all your hearing healthcare needs can be met. The additional licensing in vestibular assessment and rehabilitation, paediatric rehabilitation and cochlear implantation places this practice in one of the top specialist audiological positions in South Africa, with a wealth of experience in all clinical areas of audiology and is a very well respected and sought-after practice.

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