Hi Tim, is there an autotest doing such measurement ?
The result should be better after we adjust the gain.
It is tracked in issue 834883.

The autotest doing the measurement is called "policy_AudioOutputAllowed". Thank you for linking that relevant ticket!

+kalin to take a look

Max, Can you post test results view URL with current status?

Here's the results from the past 7 days: https://stainless.corp.google.com/search?view=list&first_date=2018-09-07&last_date=2018-09-13&test=policy_AudioOutputAllowed&status=FAIL&status=ERROR&exclude_cts=false&exclude_not_run=false&exclude_non_release=true&exclude_au=true&exclude_acts=true&exclude_retried=true&exclude_non_production=false

Lots of boards are failing the test output you posted.

The failure reason of 'RMS difference not large enough between mute and ummute' means the expected 'rms_diff < 0.4' at https://cs.corp.google.com/chromeos_public/src/third_party/autotest/files/client/site_tests/policy_AudioOutputAllowed/policy_AudioOutputAllowed.py?l=119 is failing.

Have you researched if this RMS value varies per board?

Jimmy and Yu-hsuan, is there any other verification mechanism for this test. The RMS diff seems quite unreliable.

Is https://chromium-review.googlesource.com/1221107 supposed to help here, and to what extent?

This issue has an owner, a component and a priority, but is still listed as untriaged or unconfirmed. By definition, this bug is triaged. Changing status to "assigned". Please reach out to me if you disagree with how I've done this.