The oldest musical instrument is the human voice. The voice produces sound when air from the lungs vibrates the vocal chords in the throat. The air in the hollow spaces of the chest, throat and mouth vibrates and amplifies the sound of the voice. The vibrations of the vocal chords resonate in the cavities of both the chest (in the lower register) and the head (in the upper register). Loose vocal cords produce low notes, and tight vocal cords produce high notes. The singer automatically adjusts the shapes and sizes of these cavities to produce the required notes.

As the singer is his or her own instrument, the voice is never altogether distanced from the personality.

Vocal ranges. There are four basic types of voice: soprano, alto, tenor and bass.

Menís voices are deeper than womenís because their vocal chords are longer. As a boy gets older, his vocal cords grow and his voice changes from high to low.

When men and women sing together, men usually sing an octave lower: the normal range of womenís voices is in the treble clef, and the menís is in the bass clef. Each voice has its own natural range of pitch. The highest womanís voice is the soprano, and the lowest the contralto, or alto. With the mezzo-soprano lying between the two extremes. These pitches are also within the range of boysí voices, known as trebles.

The lowest male voice is the bass and the highest is usually the tenor, with the baritone between them. Some male singers have a natural extension at the top of their range which allows them to sing in the alto, or countertenor range.