Oddly enough, even though jazz music is created within a musical system based on harmony, the art itself is focused on creating melodic improvisations which have a unique rhythmic articulation and a special relationship to the beat. This, and the fact that each performer in jazz seeks to create a unique, personalized sound, is what gives jazz its special flavor. We will begin our examination of what to listen for when we listen to jazz by focusing on the three basic elements and include a discussion of harmony as needed. Consciously or unconsciously, jazz musicians manipulate various components of sound in order to express emotion and meaning through the music they create. To a musician, tone quality refers to how rich a sound is in overtones.
Overtones are vibrations that occur simultaneously with the basic pitch.
There are an almost infinite number of overtones possible whenever a musical sound is produced. If the overtones are emphasized, the tone quality is said to be bright . If the overtones are moderately emphasized, the tone quality is clear and if very few overtones are emphasized, the tone quality is dark. It is the number and richness of overtones that allows us to tell the difference between a trombone and a clarinet, for example. One of the two instruments will have a different number of emphasized overtones than the other and will, therefore, sound brighter or darker, as the case may be.