Click or tick sound from right speaker

[Timpanogos Slim]

Got my PBP yesterday. Generally things have gone well, but at random intervals there is a tick or pop type sound from the right speaker, even with the sound muted. 

Any idea how I might troubleshoot this?

Edit: I should have specified, this happens both when using the included power adapter and when on battery power.

Also, it does go away when I mute the speaker device in alsamixer.