My boys rarely make a sound. The only time I've heard Hobbes is when he's out of sight. I think it's literally his way of calling me. For example, when I'm in the living room watching TV and he's in the kitchen, he'll make a small meow and I'll come over to make sure he's got food/water and that he's okay. That seems to please him immensely. For my kids it seems to be just their way of saying "HEY, pay attention to me!" Once I acknowledge them and pick them up for cuddles the house is silent for the night.