LoCHAid could restore hearing to millions of older people

LoCHAid is designed to be easily manufactured and repaired in locations where conventional hearing aids are priced beyond the reach of most people. The device is expected to meet most of the World Health Organization's targets for hearing aids aimed at mild-to-moderate age-related hearing loss.

Curved brainstem implant could help restore hearing

"The challenge we set for ourselves was to build a minimalist hearing aid, determine how good it would be and ask how useful it would be to the millions of people who could use it," said M. Saad Bhamla, an assistant professor in the School of Chemical and Biomolecular Engineering at the Georgia Institute of Technology. "The need is obvious because conventional hearing aids cost a lot and only a fraction of those who need them have access."

Details of the project are described in PLOS ONE.

Bhamla and his team chose to focus on age-related hearing loss because older adults tend to lose hearing at higher frequencies. Focusing on a large group with similar hearing losses simplified the design by narrowing the range of sound frequency amplification needed.

Modern hearing aids use digital signal processors to adjust sound, but these components were too expensive and power hungry for the team's device. They decided to build their device using electronic filters to shape the frequency response, a less expensive approach that was standard on hearing aids before processors became widely available.

"Taking a standard such as linear gain response and shaping it using filters dramatically reduces the cost and the effort required for programming," said Soham Sinha, the paper's first author, who was born in semi-rural India and is a long-term user of hearing aid technology.

The electronic components of the LoCHAid cost less than a US dollar if purchased in bulk, but that does not include assembly or distribution costs. Its relatively large size allows for low-tech assembly and even do-it-yourself production and repair. The prototype uses a 3D-printed case and is powered by AA or lithium ion coin-cell batteries designed to keep costs low. With its focus on older adults, the device could be sold online or over-the-counter, Bhamla said in a statement.

"We have shown that it is possible to build a hearing aid for less than the price of a cup of coffee," he said. "This is a first step, a platform technology, and we've shown that low cost doesn't have to mean low quality."

Among the LoCHAid device's drawbacks are its large size, an inability to adjust frequency ranges, and an expected lifetime of just a year and a half. The cost of batteries is often a hidden burden for hearing aid users, and the AA batteries are expected to last up to three weeks, which is still an improvement from the 4-5 day life expectancy of common zinc-air batteries in current hearing aids.

The researchers have extensively studied the electroacoustic performance of their device, but Georgia Tech said the real test will come in clinical and user trials that will be necessary before it can be certified as a medical device.