Pitch is a perceptual quality that, in speech, usually corresponds to fundamental frequency (although unvoiced sounds such as wheezes and some whistles can have a perceptible pitch without any clear fundamental frequency). The pitch of the spoken or sung voice normally varies constantly.
In Western music practice, singing is separated into notes, each of which is assigned a single pitch. If the singing consists of words, individual sylables of the words are often identified with notes, although a single syllable can be held over a series of notes. In any of these cases, there is a complicated relationship between the musical pitch (that of the note being sung) and of the continuous pitch of the voice.