i haven't the faintest idea (i keep mine sound OFF 24/7 so that i KNOW FOR SURE that it will NOT go beeping in the middle of the school day. that'd suck)
Well, when i got my 1st Tamagotchi, it would Beep when it was farting (squigly lines) would come up... But, whb i got to about gen. 3 it didnt make the beeping noise... But, with my other tamagotchis, it has never beeped... Odd, huh?!