Exclamation strange sound video camera recording

Hello! I bought a Galaxy S5 2 weeks ago and I said do some testing video! I noticed that being alone in my room, you hear a strange sound in the background as I gather with your strength, what would it be? Someone has something like I have? Please help!

Link of my sample video : https://www.youtube.com/watch?v=A_x0...ature=youtu.be

The strange sound is at 0:05 - 0:06 (strange sound begin at 0:06 )

I installed and other applications for camera and ... same problem !

Please help
HiT THANKS Button if my post helped you !