I think it might be a problem on the loopback dongle. I've played and recorded on these DUTs and found the RMS is very small. Maybe we need to change the loopback dongle on these DUTs. @kalin, could anyone handle it? Thanks.

Test command:
Record and show RMS - "arecord -f dat /dev/null -V stereo"
Play sine wave - "sox -b 16 -r 48000 -c 2 -n -t alsa default synth sine 300 sine 300"


DUTs having this problem:
1. chromeos6-row1-rack19-host13 (banon)
2. chromeos6-row1-rack20-host5 (banon)
3. chromeos2-row4-rack7-host18 (daisy)
4. chromeos6-row2-rack11-host4 (peach_pit)
5. chromeos6-row2-rack11-host5 (peach_pit)
6. chromeos6-row2-rack11-host7 (peach_pit)
7. chromeos6-row2-rack11-host13 (peach_pit)
8. chromeos6-row2-rack2-host20 (samus)
9. chromeos4-row2-rack11-host20 (mccloud)
10. chromeos4-row7-rack4-host9 (squawks)
11. chromeos4-row7-rack5-host9 (squawks)
12. chromeos6-row2-rack12-host17 (squawks)

John, can you arrange these hosts audio loopback dongles replacement with your team?
Filed b/118149227 for lab team to follow up on.

https://b.corp.google.com/u/0/issues/117509990

Wait are these all using the standard 3.5 mm audio loopback?  I moved the bug to our queue

Seems b/118149227 is resolved, and loopback dongles are replaced.
Following dashboard for the specific hosts should be looked at for improvements.