belly heartbeat

I read online today that if your husband presses his ear against your tummy he can hear the baby's heartbeat if it's in the right position. On his second try J was able to hear Aiden's quick little beat. I think it was one of the more special moments for him so far. He hasn't felt a definite kick only baby rumbles. He holds his hand on the tough belly and usually starts feeling his own pulse in his fingers. He was massaging my belly button and said that there is less and less button each day. But I think it's more and more of a button ;) But what really constitutes a button anyway?!