Mine are very vocal and the noise starts when I open the back door! They get so excited when I start opening the shed bolts and you can hear them running around and wheeking at the top of their voices. Then it is the steady munching as they gobble it all up.
When I had freeads piggy Angela in my room overnight, so I could keep an eye on her, the sound of her munching hay was so loud it kept me awake (that and the water bottle!) ;D ;D ;D