I understand that studying music has a positive effect on a child's math abilities. Math is a very broad term. The earlier a child studies music, the more rhythmic integration, movement, and learning about proportions in time space perception, strengthens the young brain. In over 1,000 American communities, early childhood music programs, such as music together, musicgarten, and kindermusik, provide parents and children with exceptional programs for developing mind and body integration. In the elementary years, playing an instrument and reading music assists in the overall development of the speech and movement, as well as language and math perception.
Music is magical because it reaches multiple levels of neurostimulation simultaneously.
However, I know of no studies that deal with calculus, trigonometry, and Mozart, other than anecdotal reports from college students who find Mozart's music beneficial during study. The earlier the better for musical participation. Yet never force an instrument on a child. Suzuki violin is a wonderful way to train the ear, hand, and heart coordination. Rhythm instruments are good in preschool years, as well as a lot of singing.