The heartbeat is clearly audible through the built-in loudspeaker with volume control. The ear phone jack enables you to listen through headphones for privacy and you can even record the sounds onto your PC and email them to family and friends.
It is becoming increasingly recognised by the medical profession that it can be beneficial for mum to be to use a foetal doppler at home in between visits to their GP or hospital. This is particularly the case where mums are anxious perhaps because they have previously had a difficult pregnancy or a miscarriage. It is also a great way for your partner to be involved especially if they are unable to attend your midwife appointments.