Well, so I just did something weird. I was super paranoid about baby, and can't pick up the heartbeat through my belly. So I stuck the probe on up in there by my cervix...
But I think I found the heartbeat! It sounds like a little train! We recorded the audio of the heartbeat from my 7w4d ultrasound, and it sounds the same only a bit faster!
Now, the disclaimer is that I have no idea WHAT all sounds I might be able to pick up in there. I found some of the same sounds I get through my belly, but then if I focused on one spot, I found this sound too. My doppler wouldn't give me a bpm, but it sounded nice and fast.