When we think of music, we think of songs, the radio, orchestra, singing, instruments playing, etc. When my baby thinks of music, he thinks of hitting the garage door, slamming Tupperware on the floor, shaking cinnamon sticks in it's container, and listening to his voice when he puts different cups to his face. Music to my baby is sound. And that makes sense, because sound is music.
By definition (English Oxford Dictionary), music is "vocal or instrumental sounds (or both) combined in such a way as to produce beauty of form, harmony, and expression of emotion." To Lukas Amichai (my baby), and every other baby I'm sure, every single sound is an expression of emotion. His smile is a full, mouth-open, ear-to-ear vibrance every time he hears sounds, and sounds are EVERYWHERE! Even in the most quiet of circumstances, we can find some sort of noise, and to Lukas, that noise is music.
Being a music teacher, I have all sorts of percussion and pitch-based instruments that are "baby friendly," but to be honest, one of Lukas's favorite music makers is a homemade shaker consisting of an empty sprinkles container and some white beans. The sound is different than his beloved egg shaker and his not-so-beloved rattles.