London –
Scientists have invented a mouthguard that helps people ‘hear’ via their tongue.
The new device uses an earpiece that communicates, via wireless technology, with a plastic retainer in the mouth. This allows it to bypass the ear, sending signals to the brain via nerves on the tongue.
These signals are then interpreted as sound.
The team behind it think it could prove a simpler alternative to invasive cochlear implants given to deaf people. It might also be useful for people with hearing loss.
More than ten million Britons – one in six – are thought to have some hearing loss, and around 10,000 wear cochlear implants.
Our ability to hear depends on sound waves entering the ear, which cause the eardrum to vibrate. These vibrations are passed to the cochlea – a coiled structure in the inner ear – where tiny hair cells send signals to the brain via the auditory nerve.
Anything that interferes with this (a blockage, or damage to the cochlea, the hair cells or the auditory nerve) can lead to hearing loss.
Cochlear implants can be fitted to bypass damaged areas of the ear. They do this using microphones and a sound processor outside the ear to transmit information to an implant in the inner ear, which then generates electrical impulses to stimulate the auditory nerve. With training, the brain learns to recognise these impulses as sound.
This is different from hearing aids, which simply amplify sound as it is passed into the inner ear.
Although cochlear implants can be highly successful for people born deaf, the required drilling through the bone behind the ear can cause additional damage. And patients must have most of their auditory system intact for the implants to work.
The new technology, being developed at Colorado State University in the U.S., uses the thousands of nerves on the tongue and the region of the brain that interprets touch sensations from the tongue to decode information from the sound waves. First, the earpiece, which sits behind the ear much like a conventional hearing aid, picks up sounds and converts them into electric impulses, which are transmitted wirelessly to electrodes in the mouthpiece. This fits over the top teeth like a brace.
When the tongue is pressed against the device on the roof of the mouth, a distinct pattern of electric impulses is felt as a tingling sensation.
The mouthpiece would be custom-fitted and the user could remove it whenever they want. The idea is that, with training, the brain will learn to interpret as sound specific patterns what is felt on the tongue.
‘It’s much simpler than undergoing surgery and we think it will be a lot less expensive than cochlear implants,’ says John Williams, a professor of mechanical engineering, who is leading the team developing the technology.
‘We think our device will be just as effective but will work for many more people. It could also help people with less severe hearing loss.
‘Our team has tested the prototype while listening to music. It is quite an enjoyable sensation.’
Commenting on the new device, Andrew McCombe, consultant ear, nose and throat surgeon at Frimley Park Hospital, Surrey, said: ‘This technique is not about “hearing” in the conventional sense, as it is not utilising that bit of the brain, or the auditory system at all.
‘It is a substitute using different senses – a bit like reading Braille, which uses touch to substitute for vision.
‘It would certainly be cheaper, and simpler, than a cochlear implant.’
*Meanwhile, tackling hearing loss in older patients may help slow cognitive decline.
A new study of 94 patients over 65 with severe hearing loss found that having cochlear implants fitted to stimulate the auditory nerve not only improved their ability to pick up on speech, but also their cognitive function.
The results, published online in the journal JAMA Otolaryngology – Head & Neck Surgery, show that 80 per cent of those with the worst cognitive function before surgery to fit a cochlear implant had improved a year later.
Daily Mail