Key points are not available for this paper at this time.
Rachel Lee Nardo, Lori A. Custodero, Diane C. Persellin, Donna Brink Fox, Looking Back, Looking Forward: A Report on Early Childhood Music Education in Accredited American Preschools, Journal of Research in Music Education, Vol. 54, No. 4 (Winter, 2006), pp. 278-292
Nardo et al. (Sun,) studied this question.