What's the analogy behind ?

Why do people ..

1. Refer to the ears as speakers (eg. speaker erundum out ah)?. Ears are input devices while the speakers are output devices.
2. What's the analogy behind "nandi maadhiri nirkuriye" ?. What I know from my limited knowledge of temples is that the "nandi" is a statue of bull in a 'sitting' position watching over the main shrine. I don't think it blocks the view or that it could be a synonym for statue, if it was, of all the statues in the world why single out nandi ?

Someone please enlighten me.