What is "alto flute"

The alto flute is a type of Western concert flute, a musical instrument in the woodwind family. It is the next extension downward of the C flute after the flûte d'amour. It is characterized by its distinct, mellow tone in the lower portion of its range. It is a transposing instrument in G and, like the piccolo and bass flute, uses the same fingerings as the C flute.

The tube of the alto flute is considerably thicker and longer than a C flute and requires more breath from the player. This gives it a greater dynamic presence in the bottom octave and a half of its range.

It was the favourite flute variety of Theobald Boehm, who perfected its design, and is pitched in the key of G (sounding a perfect fourth lower than written).

Its range is from G3 (the G below middle C) to G6 (4 ledger lines above the treble clef staff) plus an altissimo register stretching to D7. The headjoint may be straight or curved.

British music that uses this instrument often refers to it as a bass flute, which can be confusing since there is a distinct instrument known by that name. This naming confusion originated in the fact that the modern flute in C is pitched in the same range as the Renaissance tenor flute, therefore a lower pitched instrument would be called a bass.