Since Opensource.com[1] first published the story of the GNU/Linux hearing aid[2] research platform in 2010, there has been an explosion in the availability of miniature system boards, including the original BeagleBone in 2011 and the Raspberry Pi in 2012. These ARM processor devices built from cellphone chips differ from the embedded system reference boards of the past—not only by being far less expensive and more widely available—but also because they are powerful enough to run familiar GNU/Linux distributions and desktop applications.
What took a laptop to accomplish in 2010 can now be achieved with a pocket-sized board costing a fraction as much. Because a hearing aid does not need a screen and a small ARM board's power consumption is far less than a typical laptop's, field trials can potentially run all day. Additionally, the system's lower weight is easier for the end user to wear.
The openMHA project[3]—from the Carl von Ossietzky Universität Oldenburg[4] in Germany, BatAndCat Sound Labs[5] in Palo Alto, California, and HörTech gGmbH[6]—is an open source platform for improving hearing aids using real-time audio signal processing. For the next iteration of the research platform, openMHA is using the US$ 55 BeagleBone Black[7] board with its 1GHz Cortex A8 CPU.
The BeagleBone family of boards enjoys guaranteed long-term availability, thanks to its open hardware design that can be produced by anyone with the requisite knowledge. For example, BeagleBone hardware variations are available from community members including SeeedStudio[8] and SanCloud[9].
Spatial filtering techniques, including beamforming[10] and directional microphone arrays[11], can suppress distracting noise, focusing audio amplification on the point in space