[WPer]

It is a weird but interesting fact that I recently observe of my Lumia 920. When I finish playing with it and put it on my desk (actually on my purse which is on the desk because I don't want the dust on the desk ruin the camera.), if I place it a little harder, it will play a notification-like sound.
I checked all the ringer and notification sound in my phone and none of them is the sound that I heard. It does sound like the "Lattice" ringtone but not the same.

Does anyone have the same experience? What is that?

[rockstarzzz]

Your wireless charger anywhere in close proximity?

[WPer]

The wireless charger is horizontally 1 meter away and I disconnect the power of the charger but the sound is still there.

I don't think that is because of the charger because the sound it plays is not the charging notification sound.

[borasar]

Do you have NFC enabled on your phone? If so it is probably an NFC detect noise; when you put in on your purse it picks up on the Paypass in your Credit/Debit card which is NFC. Go to settings>tap+send and turn off NFC sharing, it'll stop the notification and will probably help your battery life, unless of course you need it on.

[WPer]

Aha, I found the reason. There is a RFID card in my wallet and that is the reason of the sound. Interestingly, I don't remember my 920 has this behavior in the past. Is this a recent change? Does this change mean something coming in the future?

PS: I don't have any NFC app installed on my phone.

[WPer]

Exactly, borasar! I just found it before I saw your post. Thanks!

[borasar]

No problem, glad it got sorted