Boy soprano (or treble in British English; see below) is a term applied in music to a young male singer with an unchanged voice in the soprano range. Occasionally boys whose voices have changed can continue to sing in the soprano range for a period of time.

As a boy singer approaches and begins to undergo puberty, the quality of his voice increasingly distinguishes itself from that typical of girls. While the girl's voice tends to develop gradually into the richness of the adult female voice, the voice of the boy is subject to the effects of the dropping of the larynx. The ultimate result of this profound change is that a new set of vocal ranges become available (see bass, baritone, tenor, contralto, sopranista; see also castrato). But before and as the voice drops, a uniquely rich tone develops. This brief period of high vocal range and unique color forms much of the ground for the use of the boy soprano in both liturgical and secular music in the Western world and elsewhere.

It has been observed that boy sopranos in earlier times were, on average, somewhat older than in modern times. For example, Johann Sebastian Bach was considered to be an outstanding boy soprano until halfway through his sixteenth year, but for a male to sing soprano with an unchanged voice at that age is currently fairly uncommon in the developed world, where puberty tends to begin at younger ages (most likely due to differences in diet, including greater availability of proteins and vitamins).

The use of boy sopranos (and boy altos ) in Christian liturgical music can be traced back to pre-Christian times. Boys were called upon to sing chants at Jewish religious services. St. Paul's dictum that "women should be silent in church" (mulier taceat in ecclesia) resonated with this largely patriarchal tradition; the development of vocal polyphony from the middle ages through the Renaissance and Baroque thus took place largely, though not exclusively, in the context of the all-male choir, in which all voices were sung by men and boys.

In the liturgical Anglican and English Catholic traditions, the word treble is used to refer to the boy soprano. The recent emergence of liturgical choirs including young girls has led in these traditions to both a more inclusive definition of treble which includes the higher voices of children of either sex, and to the qualified expression "girl treble," though such usage has met with opposition.

The changing of the male voice during puberty is sometimes called the breaking of the voice, to distinguish it from the less abrupt and less drastic change of the female voice.

See also

• Anglican church music
• Aled Jones