I too read that they could hear from about 18 weeks, so since just after then, I've been paying careful attention to sing and read to Lucy (especially the singing - so if you're driving around Sydney and see some crazy pg lady singing away to herself in the car don't laugh!).

We have a little routine each night where I get the monitor that lets us listen to her in the womb and try to catch the hb and some movements (she always kicks it off!) and then I read a chapter of a book.

I read that although they can hear, at this stage it's mostly Mum and indistinct sounds, later on they can make out Dad's voice as well if they're used to it, so I'll make DP read after about 30 weeks. She should be sick of my singing by then!