That's to, when an officer goes into a sick case, we have a lot of elderly folks, they are hard to hear. An officer will walk up and just turn the radio down a portion just so they can hear. You can hear it through the mike, you don't hear it through the receiver itself, you hear it through the mike so it is pretty close. Even when it's down you can hear it.
They want to have all of their attention on that person or patient and not listen to a bunch of garble.