The term 'TIMBRE' is used to describe the quality of a singing voice. It is derived from the French word for 'TONE' and is used to refer to the unique sound of a voice or instrument. TIMBRE is determined by the harmonic content, attack, and decay of a sound, as well as its overall tonal character. It is an important factor in determining the quality of a singing voice, as it can affect the clarity and emotion of a performance.