I sometimes get a weird percussion sound when I wake my phone from the lock screen and I have no idea what it is. None of my live tiles have any numbers or anything on them. What am I missing?
Oh, that's great! I tried turning quiet hours on/off, switching the setting for Lock on/off sound... And only turning NFC off was working. Thank you.
Ken, this is a known issue that dates back to older models such as the Nokia Lumia 920. Apparently it is caused by the NFC feature, and the way to stop the sound is by disabling Tap&Send under the Settings. Here's how:
First go to Settings, then look for Tap Settings > tap+send, and switch NFC sharing to Off. Hope this helps!