Help Phone makes weird noise


Hey, ppl!
Probably a weird question but it's annoying me the heck out. My phone, or most likely some app makes this weird noise time after time, like chiping/chirping sound, click click, chip chip, like camera shutter would be working all the time. The sound appears especially when I run some apps, and when I lock phone. My guess it could be some of the process killer apps, I'm currently using DU Battery saver, had DU speed booster too, but started to uninstall all the apps one by one to find out which one is making that damn sound. Before that I had also Smart app lock ( app protector ) which had this agent feature built in that would photograph anyone trying to unlock apps of phone and get the password/pattern wrong. And it sounds especially when I open and close camera app ( the standard JB one). I have shutter sound turned off though.
Crazy question, right, but maybe somebody had same issues and could share information how to get rid of that annoying chiping/clicking sound.
Thank you.