From Georgia Tech has emerged a hearing aid design that can be built for a few dollars from easily obtained parts.

Georgia-Tech-low-cost-hearing-aid
Worn around the neck in a 3d printed case, the ‘LoCHAid’ proof-of-concept is designed to be manufactured and repaired where conventional hearing aids are priced beyond the reach of most citizens, according to the university, which added that it is expected to meet most of the World Health Organization’s targets for hearing aids aimed at mild to moderate age-related hearing loss.
“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 Gatech engineer Saad Bhamla. “The need is obvious because conventional hearing aids cost a lot and only a fraction of those who need them have access.”
Georgia-Tech-low-cost-hearing-aidOne reason for high hearing aid cost is that they filter as well as amplify to compensate for uneven hearing loss across the audio spectrum, without adding noticeable distortion or noise. Adjustable digital signal processing is often used.

Bhamla and his team focused on age-related hearing loss because many older adults lose hearing in a similar way, at higher frequencies, easing the filter requirement. The design was further simplified by sticking to old-school analogue filters.
“Taking a linear gain response and shaping it using filters dramatically reduces the cost and the effort required for programming,” said fellow researcher and long-term hearing aid user Soham Sinha.
“I was born with hearing loss and didn’t get hearing aids until I was in high school,” said Sinha, now moved from Gatech to Stanford. “This project represented for me an opportunity to learn what I could do to help others who may be in the same situation as me but not have the resources to obtain hearing aids.”
The team has compared the LoCHAid user experience to: “purchasing a basic car versus a luxury car. If you ask most users, a basic car is all you need to be able to get from point a to point b. But in the hearing aid world, not many companies make basic cars.”
Georgia-Tech-low-cost-hearing-aidComponents include an electret microphone, MAX9814 pre-amp and MAX98306 Class D audio amplifier – see the paper below for a full list.
Power comes from AA (up to three weeks of operation) or lithium ion coin-cells – zinc-air batteries in current hearing aids last 4-5 days’ apparently.
Purchased in bulk, the electronic components should cost less that $1, estimates the team. To this must be added assembly and distribution.
Drawbacks include large size, un-adjustable frequency response and an expected lifetime of a year and a half.