Many early jazzmen didn’t have any formal music education and they couldn’t read music. They learned everything they knew by ear.
Their lack of formal education was one of the reasons some critics sustained the lower value of jazz in comparison to classic music. This was because they understood the term ‘know’ uniquely as a body of intellectual knowledge, but intuition and the ear can sometimes ‘know’ more than the intellect does. By listening to the bests and trying to imitate that sound, younger jazzmen intuitively learned music.
The roots of jazz are firmly planted in the African oral tradition. African masters of music orally handed down their knowledge to the younger generation without the help of any written information. The experience was normally very experimental and more fluid than written music education.
This experimentation and the lively interchange of knowledge and experience is at the heart of call-and-response techniques that are so vital to jazz performance.
Oral tradition encompasses African American culture as a whole. It influences Afro-American speech, folklore, literature and music – and it comes from long ago. Slaves from Africa often lacked a common language. Written literacy was greatly restricted to them and their descendants well into the XX century. This is why music served a crucial role in handing down black history and values, which then converge into many different, new forms of music. Jazz was one of them.
Participatory performance practices that relied on communal creation, call-and-response and a strong tradition of improvisation helped African-Americans to accommodate to the dominant white culture without being completely absorbed by it.
Ogren, Kathy J., The Jazz Revolution. Twenties America and the Meaning of Jazz. Oxford University Press, New York, 1989
Hal Galper – The Oral Tradition
Academia – Jazz Education: methodes and difficulties of teaching music derived from an oral tradition (PDF)