Suppose you've got a cold. When you wake up audiably talk to yourself - just to make you have got a voice and it's not missing somewhere - talking a bit more and coughing might even help you find it if it's gone astray.
You'd be really silly to not say anything, and 45 minutes later end up trying to talk to a guy in a computer centre when returning a laptop to not be able to make anything come out of your mouth that's intelligible, to explain why you're returning the laptop, and it's not your laptop, and the reason the person who hired the laptop isn't returning it is because he's back home in Ireland now...
You'd look very silly... well sound funny, I guess.