{"id":2369,"date":"2023-05-05T14:14:49","date_gmt":"2023-05-05T14:14:49","guid":{"rendered":"https:\/\/horizon.peachpuff-wolverine-566518.hostingersite.com\/?p=2369"},"modified":"2023-05-05T14:14:49","modified_gmt":"2023-05-05T14:14:49","slug":"improving-hearing-in-an-increasingly-noisy-world","status":"publish","type":"post","link":"https:\/\/scienceblog.com\/horizon\/2369\/improving-hearing-in-an-increasingly-noisy-world\/","title":{"rendered":"Improving hearing in an increasingly noisy world"},"content":{"rendered":"

As knowledge increases about how auditory troubles develop, new technological advances are set to cut through the clamour.<\/p>\n

By<\/em><\/strong>\u00a0\u00a0ANTHONY KING<\/p>\n

Meeting a few friends in a noisy caf\u00e9 can mean straining to hear all the conversation. It can be more of a struggle, with age, to make out what a companion is saying in a busy pub or restaurant. Whatever else may improve with time, a person\u2019s hearing does not.<\/p>\n

Yet when people complain of poor hearing, they might go for a test only to be told that nothing is wrong.<\/p>\n

Missed connections<\/strong><\/p>\n

\u2018The doctor says your audiogram is normal\u00a0\u2013 you don\u2019t have a clinical hearing problem,\u2019 said Sarah Verhulst, a professor of hearing technology at Ghent University in Belgium.<\/p>\n

That doesn\u2019t mean the people were imagining their difficulties, however. The hearing trouble may lie elsewhere.<\/p>\n

Ageing and loud noise cause wear and tear on the hairs or nerve cells in the inner ear. This damage is what most tests are designed to detect.<\/p>\n

But the auditory nerve itself can get impaired, reducing the number and quality of points of connection to brain cells. These junctions are known as synapses.<\/p>\n

\u2018This is a new kind of hearing impairment where the synapses attached to hair cells that transmit the sound to the brain are damaged,\u2019 said Verhulst.<\/p>\n

This synapse harm can be missed in standard hearing tests.<\/p>\n

Amplifying sounds using a hearing aid can compensate for fewer hair cells but is less effective in cases of injury to the nerve and its connecting synapses.<\/p>\n

Nerve numbers<\/strong><\/p>\n

In healthy hearing, each hair cell has about 15 nerve connections that transmit to the brain, according to Verhulst.<\/p>\n

While only one synapse is needed for sound detection, having multiple transmission routes becomes important when trying to tune into specific sounds in an environment with many of them \u2013 such as a crowded bar with the music turned up.<\/p>\n

With 15 independent channels to transmit the same sound from the inner hair cell to the brain, a person can average this signal and tune out the background acoustic noise. In a noisy environment, someone with fewer synapses will struggle to distinguish sounds.<\/p>\n

Auditory difficulty increases with age and can\u2019t be solved with hearing aids. As part of the EU-funded\u00a0RobSpear<\/a>\u00a0project, Verhulst developed an alternative in her laboratory in the Belgian city of Ghent.<\/p>\n

She measured brain activity using electroencephalograms, or EEGs, to diagnose loss of hearing synapses in people. She then devised algorithms to tweak the sound in a way that is helpful to the remaining nerve connections\u00a0\u2013 for example by enhancing silent periods and sharpening peaks in sound.<\/p>\n

\u2018We wanted to stimulate the nerves optimally, but first we needed to understand them,\u2019 Verhulst said.<\/p>\n

Following the end of RobSpear, which ran for five and a half years into 2022 and was funded through the European Research Council, she hopes her algorithms will be used in all kinds of wearables including hearing aids, headphones and other devices.<\/p>\n

The new algorithms could help everyone in environments with lots of background noise, not just people with hearing impairments.<\/p>\n

Alarming loss<\/strong><\/p>\n

More than\u00a0190 million<\/a>\u00a0people in the 53 countries that make up the World Health Organization\u2019s European region live with some degree of hearing loss. This figure is projected to rise to over 230 million by 2050.<\/p>\n

Modern-day machines, traffic and entertainment all mean that people are more exposed to loud sounds than their ancestors.<\/p>\n

\u2018This sort of synapse damage is normal in the new generations who are constantly exposed to noise, such as listening to headphones,\u2019 said Verhulst. \u2018People are going to be hearing impaired at a younger age than for our previous generations.\u2019<\/p>\n

Today, those who are deaf or severely hard of hearing can benefit from a cochlear implant. This small device bypasses damaged parts of the ear and stimulates the auditory nerves.<\/p>\n

\u2018Cochlear implants are amazing devices for hearing-disabled people,\u2019 said Haluk Kulah, a professor of biomedical engineering at the Middle East Technical University in Turkey\u2019s capital Ankara.<\/p>\n

With existing devices, however, a receiver needs to be attached on the ear close to the auditory nerve.<\/p>\n

One major complication is that the external part of the hearing aid is power hungry and users sometimes need to change the battery as often as every day.<\/p>\n

There are other disadvantages too. Hearing aids are expensive and vulnerable to damage from exposure to water or physical activity. They can also be lost or create for a stigma for wearers. Furthermore, they aren\u2019t very aesthetic and limit users\u2019 activities such as swimming.<\/p>\n

Promising device<\/strong><\/p>\n

Kulah spent six years working on a device that will avoid all of these troubles by developing a high-performance, fully implantable cochlear implant as part of the EU-funded\u00a0FLAMENCO<\/a>\u00a0project, which ended in 2022. This initiative was also ERC funded.<\/p>\n

One of the challenges was how to fit the acoustic sensor and electronics, as well as a reliable power source, all within a space of around five by five millimetres. And other hurdles confronted Kulah.<\/p>\n

\u2018The electronic circuit should consume minimal amounts of power and any battery should last for five years or more,\u2019 he said.<\/p>\n

One idea was to use sound waves to help charge the battery, an approach shown to work in lab tests with hearing-impaired guinea pigs. The result was a cochlear implant with the lowest power consumption recorded, according to Kulah.<\/p>\n

More recently, his lab achieved wireless recharging of the device, making it even more convenient for users.<\/p>\n

Kulah believes that almost everything possible in a university setting has been done and that it\u2019s time for the next phase to begin: commercialisation.<\/p>\n

Earlier this year, he received fresh\u00a0ERC funding<\/a>\u00a0to move the device ever closer to patients. His plan is to work with four companies already involved in the production of cochlear implants.<\/p>\n

Research in this article was funded via the EU\u2019s European Research Council (ERC). The article was originally published\u202fin <\/em>Horizon<\/em><\/a>, the EU Research and Innovation Magazine.\u00a0<\/em><\/p>\n

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