When I went for my first scan at week 8, we could already hear the heartbeats. The gynae increased the volume so that it is audible. Same for my second scan at week 12. The gynae will automatically play the heartbeats for us. (I always tear up instantly when I hear the heartbeats, cos it makes everything feel soooo real)
It's actually not how loud the heartbeat is but the machine. The sonographer will increase the sound for you to hear and normally just for a while. On your normal consultation also you will still get to hear your baby's heartbeat with the doppler
for mine(KKH)they only let you hear the baby's heartbeat when you go for consultation.My baby's heartbeat was not as loud as other cause he keeps running away everytime they want to check up on him