From Nordic: "Smart Remote 3 for nRF52 Series: How to test and debug audio processing"
Smart Remote features advanced audio processing. To achieve high quality of voice, it supports PDM microphones, noise reduction, DSP equalizer, and 4 different codecs. Such an advanced processing leads to one question: how to get the best out of it? The answer is Audio Probe.
Audio Probe lets you capture the audio data at any stage of audio processing in firmware. Alternatively, you can also send your audio file from the computer to the nRF52 device, simulating audio input. For example, it can be used to measure what is the impact of the casing on the microphone input, or to see how audio algorithms perform on known data.
Audio Probe is available for Smart Remote developers as part of the Linux Host LiveCD.