The highest part of a polyphonic composition.the treble voice is a voice in the higher register. The word is generally used for the unbroken voice of boys, although the register may be similar to that of the female soprano. Treble instruments are instruments of higher register and the g clef in use for this register is commonly known as the treble clef. Originally the treble or triplum was the third part added above a duplum or second additional part, lying above the lowest part, the tenor of the medieval motet.