This is relevant because it indicates that harmony is a deeper cognitive measure than unexamined phrases such as, "pleasing to the ear" would suggest. Much research in music cognition seeks to uncover these miscellaneous mental processes involved in listening to music, which may seem intuitively simple, yet are vastly intricate and complex.
Many types of music, such as traditional blues and folk ragtime were originally preserved in the anamnesis of performers, and the songs were handed down orally, or aurally (by ear). When the composer of rock-and-roll is no drag out known, this air is often classified as "traditional". Divers musical traditions have different attitudes towards how Music For TV and where to make changes to the original source material, from quite strict, to those which demand improvisation or modification to the music. A culture's history may also be passed by ear through song.