When a tailor is making an item of custom-fit clothing, they first take the client's measurements, then adjust a mannequin known as a tailor's dummy, to match those measurements. That way, as they're making the clothing, they can check the fit on the dummy, instead of repeatedly bringing in the actual client. When it comes to hearing aids, however, clients often need to pay follow-up visits to the hearing clinic, in order to get the device adjusted so it suits their particular type of hearing loss. Recently, though, a team from the University of Essex have developed software that creates virtual "hearing dummies." These could allow for hearing aids to be tailor-made for each client's needs, right from the start.
"Today's hearing aids don't help to separate sounds - they just amplify them," said project leader Prof. Ray Meddis, of the university's Department of Psychology. "So they often make everything too noisy for the wearer, especially in social situations like parties, and some wearers still can't make out what people are saying to them. They find the whole experience so uncomfortable that they end up taking their hearing aids out. This discourages them from going to social occasions or busy environments and may result in them withdrawing from society."
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Meddis and his team developed a new type of hearing test, that more accurately identifies what type of hearing loss a client has - typical "threshold tests" simply measure how quiet of a sound a client is still able to hear, whereas Meddis' system places an emphasis on a variety of higher-level sounds, which users are more likely to encounter on a daily basis.
Using the results of these tests, a computer algorithm is adjusted until it matches those results - this is the so-called hearing dummy. In the immediate future, this model could be used to indicate what is causing the hearing loss, which could then potentially be addressed. In the long run, however, the model could be used for fine-tuning custom hearing aids. Instead of just boosting audio levels, each device would make the specific audio adjustments needed by each individual client.
"Our work has shown that, when it comes to hearing impairment, no two people are alike," said Meddis. "That's why two people with apparently similar hearing thresholds often react very differently to their hearing aids."
Hearing dummy-created hearing aids could be available within four years, according to U Essex.
Besides the unique testing procedure and the hearing dummies, Meddis is also developing a new type of hearing aid, that is said to more closely mimic how the human ear works. The device is currently still a lab-scale prototype, although a miniaturized version is in the works.