There is currently an interest in developing musical intelligence in babies through recordings.
The web site "babygenius.com" offers classical music CDs and tapes particularly selected as appropriate for children's mental growth. Exposure to classical music probably does make babies smarter in certain ways, but exposure to simpler music is also important, for it develops the 'the singing ear', and learning to sing at a young age will enhance general mental development.
On the web, I found a confusing array of companies and theoretical claims. One company was selling recordings touted through research into "The Mozart Effect". Another company was selling recordings of music composed according to findings in fetal research.
There are companies that combine recordings with parental modeling and teaching of young children.
The Kindermusik company sells recordings, but also gives classes to parents with their children. The premise of the KinderMusik program is that the parent is the child's first and most important music teacher. Their program is designed to help parents do this. The parents come with their infant, toddler and preschool children to classes given by their licensed teachers. The teachers encourage the parents to sing to their children and to engage in musical activities with them. This program is cost prohibitive for working class families, and lacks a suitable system for preparing young children for later note-reading. The way to improve musical aptitude in children of working class families is to introduce recordings and DVDs primarily as entertainment, with only a brief pitch as to their music education value.
The Suzuki method of violin instruction begins with recordings at birth and continues with parental modeling. For the Suzuki method, the parent must invest some time in learning to play the violin, so that the child learns first primarily through the deep impulse to imitate the parent. With early parental modeling, then encouragment and praise as the child begins lessons, the child progresses quickly past the level of the parent. This method is good for parents who can afford to buy the violin and who have the time to learn to play it. I believe the Suzuki method was able to be introduced effectively through the openness of the Japanese culture after its devestating loss of World War II. Afterwords, the post-war boom and the prosperity of the professional class created a market abroad. We have learned a great deal from Suzuki and his philosophy of music education in the home. We wish to make these insights 'marketable' to lower income families.
There are methods of teaching sight-singing, or vocal music reading, to primary age children.
John Bertalot's book, "Five Wheels of Successful Sight-Singing" (Augsburg Fortress) presents some great ideas, and you don't have to be licensed to learn them and use them; all you have to do is buy the book. It advocates teaching children in small groups, having children take turns reading music, and not playing the melody for them. It's only problem is that it employs the full scale at the outset. This is fine for children eight years and up, but the pentatonic scale should be used for younger children. Emphasizing the full scale too soon without sufficient prior exposure to the pentatonic scale could cause tuning problems that would persist throughout life.
The Kodály method is used in many public schools today. Using pentatonic folk songs and even simpler nursery rhymes, the method focuses on the notes of the scale which children can sing in tune. The Kodály method begins with the "children's interval", the minor third, in its falling or falling-and-returning form. This instinctive 'children's interval' is very effective for children's early experiments with singing. I call it the "musical embryo". Kodály teaching begins too late, in first grade. Children should be hearing and possibly singing the children's interval at the toddler age, and singing nursery rhymes which expand from this pitch set at the preschool age. The Kodály method also uses solfege ("Do-Re-Mi"), which is rather too left-brain for early pitch development (pitch is right-brain, words like 'Do-Re-Mi' are left brain entities). I think that a simpler, less 'wordy' pitch organizing system will speed younger children's progress toward singing the full scale in tune and toward reading music effectively at a young age. Full-scale Solfege should not be introduced until age nine.
On the whole, our culture emphasizes instrumental instruction over vocal music reading. Vocal music's importance both before and after learning to read music is little understood. Vocal music trains the ear and makes the brain think. It is the most direct and least expensive way to develop born aptitude at a young age.
Reviewing what is out there in teaching, it seems that what is needed is a child-friendly parent-friendly method for getting parents to teach younger children before first grade. This is essential to foundational aptitude. Foundational aptitude in music aids general mental development. It is for every child. It is not only for children who will grow up to be professional musicians, but also for children who will later work as non-musicians.
Foundational aptitude is what a whole culture shares with its children, not just what the talented share with the talented. We have a cultural duty to all our children- the ordinary as well as the talented. The 'elitist' association of 'classical' music and 'reading the notes' must be overcome. Every child should be exposed to pitch structures natural to the singing ear from birth. Every child should be able to match pitch before age six. Every child should have instruction in vocal music reading before age nine. Ordinary children should take up an instrument after demonstrating ordinary singing ability by age nine. Exceptional children should take up an instrument at an early age, as early as age four, after demonstrating unusual singing ability for that age. As these points are more and more proven, as I believe they will be, cultural resistance to the responsibility of music education will be shown to be inexcusable.