4mic hat stretch-lite-2018-11-13 static noise

I have installed the 4mic hat on raspberry pi 3 running stretch-lite-2018-11-13.

I ran the arecord example and when I play it back I get loud static and I can hear very faintly the recorded speech.

I have tried this with various releases of stretch-lite and I get the same loud static. I also tried the stretch-lite builds from <LINK_TEXT text=“https://v2.fangcloud.com/share/7395fd13 … 6fd4792fe5”>https://v2.fangcloud.com/share/7395fd138a1cab496fd4792fe5</LINK_TEXT> and I get the same results.



Can you help?



arecord -Dac108 -f S32_LE -r 16000 -c 4 hello.wav



also arecord -L does not match that shown in the installation instructions. Mine is missing:

capture

dmixed

array

default:CARD=seeed4micvoicec

seeed-4mic-voicecard,

Default Audio Device



arecord -L

null

Discard all samples (playback) or generate zero samples (capture)

playback

ac108

default

mic

speaker

sysdefault:CARD=seeed4micvoicec

seeed-4mic-voicecard,

Default Audio Device

dmix:CARD=seeed4micvoicec,DEV=0

seeed-4mic-voicecard,

Direct sample mixing device

dsnoop:CARD=seeed4micvoicec,DEV=0

seeed-4mic-voicecard,

Direct sample snooping device

hw:CARD=seeed4micvoicec,DEV=0

seeed-4mic-voicecard,

Direct hardware device without any conversions

plughw:CARD=seeed4micvoicec,DEV=0

seeed-4mic-voicecard,

Hardware device with all software conversions



also my .asoundrc is:

pcm.!default {

type asym

capture.pcm “mic”

playback.pcm “speaker”

}

pcm.mic {

type plug

slave {

pcm “hw:1,0”

}

}

pcm.speaker {

type plug

slave {

pcm “hw:0,0”

}

}

UPDATE: I tried again with fresh builds of stretch and stretch lite 11-13-2018 + latest update and it worked OK. But then I installed Google Assistant SDK and SEEED steps for 4mics_hat google_assistant.py, which is no longer contained in the newer 4mics_hat, and I got the same loud static problem. I will troubleshoot some more with fresh installs and try to pin down what may be causing the problem.

I did further testing and found out that my 4mics_hat board records OK for the first few minutes and then gets loud static in the recording. I looked at the wav file waveform with audacity and I can see that mics 1,3,4 have loud static, mic 2 has some static. I will be investigating further.