I never heard the heart beat for my first so guess it varies by trust.
My nhs scans don’t have sound. I had a private scan and they did the heartbeat. Our midwives don’t check the heartbeat with a Doppler until the 26 week appointment. But some do check at the 16 week one.
Mine turned it on for a few seconds at my 12 weeks scan, and mentioned that it’s not too safe to do it for a long time for a baby