Deviation From Microphone Magnitude Values

Hi all, I just got to try out the board today. I ran mic_demo and realised that 2 mic channels were consistently showing higher magnitude values as compared to others. I placed the board in different parts of the room but there wasn’t any difference. Even in a dead quiet room, the readings for those 2 channels were considerably higher.

Is this considered a hardware issue or can it be resolved somewhere in the sources?

Hello @bagofchips

You could verify each microphone channel with micarray_recorder demo. With them you record sound in a raw file for each channel.

First you need to install sox:

sudo apt-get install sox

You can format these files with:

sox -r 16000 -c 1 -e signed -b 16  mic_16000_s16le_channel_0.raw ch0.wav

Turn the volume up with ALSA in your raspberry:

alsamixer

Finally connect speakers or a headphone in your Rasberry and play wav files with:

aplay ch0.wav

Let me know how the test is going?

BR,

Kevin Patino

Hi Kevin, thanks for replying. I can record them just fine. It is just that those 2 values always seem to be higher regardless of location. Anyway, I think I’ll investigate further in future.