I've got brand new Moto X Style. Great phone, but I have a weird issue which I'm trying to diagnose.
My phone sometimes makes that volume change acknowledgement noise without any interaction. If you have an AOSP phone, try lowering or raising the media volume using the rocker, the little noise the phone produces to help you judge if the volume is low/high enough; that one.
It does it if the phone's screen is on or off, if the phone is being actively used or sleeping.
This isn't a major issue, but it is a bit annoying. It does it without any pattern I'm able to identify. It even does it when it is on Do Not Disturb/Priority Only. I've captured a logcat which covers few moments before and few moments after this issue occuring, but I'm not really able to make sense of it.
It is not the NFC sound. I know how to recognise that, and it does it when far away from any RFID chips. I've also opened the Notification History panel, and it shows nothing there.
Can anyone help me read it and point towards anything that might give me a bit more of a clue?
If more of the logcat is required I can provide more.