There is no longer any doubt that there is a significant link between early music instruction and cognitive growth in certain other, “nonmusical” abilities, such as math, memory, and spatial-temporal reasoning. In fact, studies focused specifically on music for young children even suggest that these cognitive gains increase according to the number of years that students engage in active music learning, and even that the younger children are when they begin, the greater the gains will be!
For more detail see:
The Impact of Music on Mathematics Achievement by Deanne Kells, M.A. http://www.kindermusik.com/Classes/Downloads/ImpactOfMusicOnMath.pdf
Discovering Mathematics Through Music by Heidi Gilman Bennett
Research Highlights (Toddlers) - http://www.kindermusik.com/Classes/Downloads/MusicAndMathOTFinal.pdf
Research Highlights (Preschoolers) - http://www.kindermusik.com/Classes/Downloads/MusicAndMathITFinal.pdf