Why KKH don’t play sound for heartbeat.. any nurse can share why this protocol?

I think it's a safety thing lah, they want to limit unnecessary ultrasound exposure, especially in early pregnancy when you're just confirming dates and viability. Some hospitals are stricter about this than others, but KKH's approach is basically "we show you it's there, that's what matters" rather than adding extra time for the audio. My friend went there for her dating scan too and had the same experience, so it does seem to be their standard practice rather than anything to worry about.