"VOCALOID is a vocal-synthesizing software that enables song writers to generate authentic-sounding singing on their PCs by simply typing in the lyrics and music notes of their compositions. The software synthesizes the sound from "vocal libraries" of recordings of actual singers, retaining the vocal qualities of the original singing voices to reproduce realistic vocals. The software also features simple commands that enable users to add expressive effects - such as vibrato and pitch bends - to their synthesized vocals. Additional releases to the range of vocal libraries currently available will broaden the range of voices and singing styles that can be generated by VOCALOID. VOCALOID can generate singing in Japanese and English. It runs on Windows 2000/XP."

http://www.vocaloid.com/en/