A Maker by the name of “Ojoshi” has designed a DIY intelligent hearing aid prototype powered by an Atmel-based Arduino Mega (ATmega1280). The project, originally posted to Instructables, was recently featured on the HackADay website.
So, just how does the DIY hearing aid prototype work?
First, the platform employs an electret to capture audio, subsequently running it through a pre-amplifier to increase the gain 100x. The next stage consists of four filters – neatly dividing the input signal by frequency into four parts, which are passed into four LTC6910 programmable gain amplifiers, allowing the Arduino to control the gain of each channel. The LTC6910 then takes three digital inputs used to set the gain value.
“To determine which gain to use for each frequency band, the Arduino needs to know how much power is in each band,” explained HackADay’s Eric Evenchick. “An envelope detector averages the signal, which can be read by an analog input on the Arduino. Using this information, the hearing aid can boost specific frequencies when it detects conversation.”
As Evenchick notes, this hearing aid won’t quite fit in your ear, although there is quite a lot of interesting signal processing/action happening on the prototype.
Interested in learning more about Ojoshi’s DIY hearing aid prototype? You can check out the project’s official Instructables page here.