If they make quieter, lower pitched, wuffling kinds of sounds, they are pretty happy.If they make louder squealing sounds, they aren’t so happy.They will beg for food with a high pitched whiny squeal whenever they hear rustling paper. They think it’s lettuce.
My guinea pigs as a kid were pretty easygoing—as far as guinea pigs go. They are pretty high strung, but that doesn’t mean they are actually terrified all the time. They aren’t like cats—they are extremely high energy. If they get too anxious, they will go inside a box and chew it up from the inside to calm down.