As mentioned in studies, babies can already hear starting 4-5 months in utero. The baby can hear the mother’s heartbeat, other bodily sounds and also those outside the womb. There have been thoughts about letting your child listen to classical music through your belly before birth, and that this could make them smarter than they are. This is called the “Mozart Effect.”
There are many kinds of ‘smart’ and one of them is auditory intelligence. I believe that this can be developed through music therapy from the womb, beyond. It allows the child to be familiar with different kinds of sounds and their vibrations, so that he or she could acquire an instinctive skill in identifying and, or executing sound.
It has been said that loud music can affect the fetus’ developing ears, that is why it is not advisable to play some heavy rock (unless up to a soft volume). Jazz and classical are recommended due to their mentally stimulating note and chord patterns which could also be good for developing the child’s state-of-mind. Take your pick. http://www.musiciansfriend.com/sg-guitars