Cape4all is a Multi-Microphone Audio Extension Cape for BeagleBone Black
Cool project board available for the BeagleBone Black – with complete board and schematic files available on GitHub. Opensource.com reports capes like this are being used in conjunction with beamforming to operate as spatial hearing aids – brilliant!
Open Hardware Multichannel Sound Interface for Hearing Aid Research on Beaglebone Black
Hardware Design Files
The published Beaglebone AD/DA Cape schematic and board layout files were developed by the Institute of Microelectronic Systems at Leibniz Universität Hannover together with the videantis GmbH within DFG Cluster of Excellence EXC 1077/1 “Hearing4all” They are published unter the CC BY-NC-SA 4.0 license.
Kernel Driver Files
These were developed by 64Studio for HörTech gGmbH. They are published under the GPLv2 license.
See the respective directories for the full license text.
The Cape4all, presented recently at the Linux Audio Conference in Berlin, Germany, runs at a sample rate from 24kHz to 96Khz with as few as 12 samples per period, leading to internal latencies in the sub-millisecond range. With hearing enhancement algorithms running, the complete round-trip latency from a microphone to an earpiece has been measured at 3.6 milliseconds (at 48KHz sample rate with 16 samples per period). Using the speed of sound for comparison, this latency is similar to listening to someone just over four feet away without a hearing aid.
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