Timbre is the character or quality of a musical sound. There are many different words we can use to describe the timbre of a sound: bright, dark, brassy, reedy, harsh, noisy, thin, buzzy, pure, raspy, shrill, mellow.
When we describe the timbre of a sound we do not describe how loud the sound is (dynamics) or how high or low the sound is (pitch).
Just a Closer Walk With Thee- Pete Fountain
In this version of Just a Closer Walk With Thee, the clarinet plays the melody throughout. When it plays low at low pitch it sounds mellow and breathy, but when it plays at a high pitch it sounds bright and shrill.
Have a listen below...