Although many wouldn’t consider it a musical instrument, the human voice is arguably the most expressive and important instrument of all. It is thought that music originated with singing and their is literally no culture in the world that does not have a tradition of singing. Even in cultures where music has been frowned upon, the human voice invariably provides an exception.
One advantage singing has over other musical instruments is that it allows music to be combined with words and lends a heightened expression to words that they would not have when merely spoken or declaimed in a dramatic fashion.
The New Grove Dictionary of Music and Musicians describes the value of singing our culture like this;
[S]inging (or incantation) played a vital role in many early forms of religious ritual, and in the early theatre. Even outside religion, singing has long been held to have moral and cultural value. Aristotle quoted the bard Musaeus, ‘Song is man’s sweetest joy’, and went on to warn against using musical instruments, such as the aulos, which interfere with or prevent the act of singing. Athenaeus (Deipnosophistae, 2nd century) reported that ‘it is no disgrace to confess that one knows nothing, but it is deemed a disgrace among them to decline to sing’. In the history of Western civilization, and of other civilizations, an ability to sing well has repeatedly been viewed as a mark of culture and humanity.