volume control, sound modes and disabling of all sounds (such as sounds triggered by app startups, charging, and connections to headphones, etc.) can be automatically controlled. certain types of volume control not possible through device settings can also be edited. also, with a feature which disables all sounds, you can even disable the shutter sound on your standard camera app. how to invalidate and note: this app invalidates all sound of the device by switching the master mute setting. if you turn on invalidation manually, the entire device's sound will be disabled until you turn it off manually. please note that if you uninstall the app while manually disabling the invalidation, you will need to reinstall it and cancel the invalidation, so please disable invalidation before uninsta