Sept 2020 Science Magazine
Saad Bhamla models his do-it-yourself hearing aid, built with a soldering iron and cheap supplies
As an undergraduate in Mumbai, India, Saad Bhamla wanted to do something nice for his maternal grandparents: Buy them a pair of hearing aids. But the prices were shockingly high—and far beyond his means. Now, 15 years later, the bioengineer has invented a device to help grandparents across the globe: a do-it-yourself hearing aid made from inexpensive, easy-to-find parts. The no-frills device, described in a new study, could help restore hearing to millions suffering from age-related hearing loss—for less than the price of a bottle of water. The new device is “incredibly compelling,” says Frank Lin, an ear, nose, and throat doctor at the Cochlear Center for Hearing and Public Health at Johns Hopkins University who was not involved in the work.
Globally, 230 million people aged 65 and older experience age-related hearing loss. Typically, high-pitch sounds become harder to distinguish, like electronic beeps and speech sounds such as “s” and “th.” Conversations can seem mumbled, and background noise feels distracting and invasive. Such deficiencies can be isolating, Lin says, and his research suggests they can also accelerate cognitive decline.
To regain their abilities, many seniors turn to hearing aids. Custom hearing aids amplify sound in the exact frequencies that the listener cannot hear. But at nearly $5000 a pair, these devices are “practically a luxury item” for many in low- and middle-income countries, says Bhamla, who specialises in “frugal science” at Georgia Institute of Technology. Lower grade hearing aids are cheaper, but they can’t be customised, and they still cost up to $500. They’re like “cheap earphones in an airplane,” Bhamla says.
Inspired by his grandparents and a hearing-impaired colleague—who is first author on the new paper—Bhamla and his team set out to develop a cheap hearing aid built with off-the-shelf parts. They soldered a microphone onto a small circuit board to capture nearby sound and added an amplifier and a frequency filter to specifically increase the volume of high-pitch sounds above 1000 hertz. Then they added a volume control, an on/off switch, and an audio jack for plugging in standard earphones, as well as a battery holder. The device, dubbed LoCHAid, is the size of a matchbox and can be worn like a necklace. At bulk rates, Bhamla says, it would cost just under $1 to make. But anyone with the freely available blueprints and a soldering iron can make their own for not much more—maybe $15 or $20, Bhamla says. The parts are easy to source, he says, and putting them together takes less than 30 minutes.
Next, Bhamla and his colleagues tested the device. They found that it boosted the volume of high-pitch sounds by 15 decibels while preserving volumes at lower pitches. It also filtered out interference and sudden, loud sounds like dog barks and car horns. Finally, tests with an artificial ear revealed that LoCHAid might improve speech recognition, by bringing conversations closer to the quality heard by healthy individuals. It complied with five out of six of the World Health Organization’s preferred product recommendations for hearing aids.
Its simplicity has a few drawbacks, however. The device can’t be fine-tuned for individual needs or adapted to treat other hearing issues. And even though it’s waterproof and shock resistant, the scientists anticipate that LoCHAid’s parts will wear out after about a year and a half. Its bulky size might deter some users, Bhamla says, although a smaller version is in the works. But engineering is only half the battle. Until LoCHAid is clinically tested, it cannot be sold as a “hearing aid” in most countries—including the United States. Ultimately, Bhamla wants to get an approval to sell the device over the counter without a prescription, like ibuprofen or reading glasses. “It’s something we’re still figuring out,” he says.
The next step is getting people to use the devices. In low- and middle-income countries, only 3% of people with age-related hearing loss wear hearing aids, and in countries like the United States, the adoption rate hovers at about 20%, according to Bhamla. Aside from concerns about cost, Bhamla says, “a lot of people don’t realize they have hearing loss … and then there’s the social stigma of wearing the aid.” But if these cheap, colourful devices take off, they could benefit many people on the brink of cognitive decline, Lin says. “Theoretically, if you treat hearing loss, you might modify those pathways and reduce the risk of dementia.” Bhamla wants biomedical devices to be as cheap and accessible as consumer electronics. He still remembers the shock of learning that he couldn’t afford to help his grandparents. “I thought owning a laptop and a cellphone meant I had the means to buy hearing aids, but then I realised how expensive they were,” he recalls. “It was sobering.”