A QUARTET is a musical ensemble consisting of four performers. The term 'QUARTET' can refer to any group of four musicians, but it is most commonly used to describe a group of four singers or string instruments. The most common QUARTET consists of a soloist, an ALTO, a tenor, and a bass. The soloist is the lead singer or instrumentalist, while the ALTO, tenor, and bass provide harmony and accompaniment. The term 'QUARTET quarter' refers to a specific type of QUARTET that is made up of four singers or string instruments in the same range.