TREBLE (a doublet of " triple," three-fold, from Lat. triplus, triple; cf. " double " from duplus), the term applied, in music, to the high or acute part of the musical system, as opposed to and distinguished from the " bass," the lower or grave part. The middle C is the practical division between the parts. The word is also used as equivalent to the " soprano " voice, the highest pitch or range of the human voice, but generally it is confined to a boy's voice of this quality, " soprano " being used of the corresponding female voice. The treble-clef is the G-clef on the second line. The origin of this application of the term " treble," triplus, threefold, to the highest voice or part is due to the fact that in the early plain-song the chief melody was given to the tenor, the second part to the alto (discantus) and where a third part (triplum) was added it was assigned to the highest voice, the soprano or treble.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)