I always check out what FF says each week - there's a section about what your baby (& body) are up to...

Week 17
He can probably hear by now as the ossicles (the bones that pass sound to the inner ear) have hardened and the portion of the brain that receives signals from the brain is under development. Your baby is getting used to the sound of your heartbeat and blood passing through the umbilical cord, but may be startled by loud noises. Your baby is aware of some things in the outside world, including sounds and light. If you let the sun shine on your belly, your baby may be able to perceive a warm red glow.
We have been reading to Munchkin in the last few weeks & he absolutely loves it. Also at 20w we went to see the Queen musical We Will Rock You & I'm sure he was dancing to some of the songs LOL!!