I've just purchased a sonoline B Doppler I received it today in the post and couldn't wait to try, I searched for mine and my partners heartbeats they show up straight away around 80bpm. After some hesitation tried to find my babies heart beat after about 10 minutes of searching and nearly giving up finding it for today it came through loud and clear around 137-141 beats per minute. It's amazing and so comforting that this works in the comfort of your own home meaning I can hear my babies heartbeat whenever I want!