Most Windows Phone 7 owners should know this annoyance by heart now: There is no way to disable the shutter sound in the camera app. To be precise, even a muted, silent, volume level 0 phone will make the sound. The reason for this is not clear, but one thing is for certain: it's annoying. 

Thankfully, we've discovered a method to disable this sound, and it works like a charm. Burried deep in the registry is an option that allows the shutter sound to bypass the device's audio level. Disabling this will make the shutter sound follow the volume level of the device, including muting it completely.

To do this, you need the TouchXperiance registry editor and a jailbroken/developer unlocked device. After installing the registry editor, navigate to 

HKEY_LOCAL_MACHINE\Audio\StreamClass\Output\10

and set "BypassDeviceGain" to 0. You may need to reboot the device after applying these settings.

Now, in the camera application, the shutter sound should follow the device's audio settings. Enjoy!

[Via: XDA Developers]