Unborn babies, relaxing in a puddle of amniotic fluid, will start to notice sounds by the third trimester. Though their hearing will be muffled, they can still pick up on and respond to their parents' noises.
This video is a prime example of an unborn baby's hilarious response to her parents making a commotion.
Even though a mother's womb is a lovely place to spend nine months, this particular baby is probably feeling pretty confused by the unfamiliar noises (many refer to them as "raspberries") her father is blowing onto her mother's belly.
If you've never heard of the term "raspberry," think of it as a tickling sensation that results in a farting sound.
Or just watch this video and you'll see what we mean.