VOCAL IN MUSIC

Vocal music is a type of singing performed by one or more singers, either with instrumental accompaniment, or without instrumental accompaniment (a cappella), in which singing provides the main focus of the piece. ... Music without any non-vocal instrumental accompaniment is referred to as a cappella.

Vocal music often has a sequence of sustained pitches that rise and fall, creating a melody, but some vocal styles use less distinct pitches, such as chants or a rhythmic speech-like delivery, such as rapping. As well, there are extended vocal techniques that may be used, such as screaming, growling, throat singing, or yodelling. Vocal music is probably the oldest form of music, since it does not require any instrument besides the human voice. All musical cultures have some form or type of vocal music.

HOW CAN WE SAY A SONG IS VOCAL? 

Vocal music is a genre of music performed by one or more singers, with or without instrumental accompaniment, in which singing provides the main focus of the piece. Music which employs singing but does not feature it prominently is generally considered instrumental music as is music without singing.