Woodwinds

The modern flute is made of metal but still counts as a woodwind, because what matters is how the sound starts, not what the tube is made of.

Air in a tube

Every wind instrument is a tube of air. When the air inside vibrates, it sounds a note, and a longer column of air gives a lower note. The holes and keys along the tube change the length of the vibrating column. Close all the holes and the column is at its longest, so the note is the lowest. Open holes from the bottom up and the effective tube gets shorter and the note rises. Woodwinds are sorted by what sets the air vibrating at the top of the tube.

Flute: no reed at all

The flute has no reed. The player blows a narrow stream of air across the edge of a hole, like blowing across the top of a bottle, and the air flips back and forth over that edge. Theobald Boehm redesigned the flute in the nineteenth century, and in 1847 he introduced a model with a cylindrical metal tube and a new key system. Most flutes today follow his design. The piccolo is a half-size flute that sounds an octave higher. Beethoven gave it a part in the finale of his Fifth, together with a contrabassoon and three trombones.

Oboe and bassoon: two reeds

The oboe uses a double reed: two thin blades of cane tied together, which the player squeezes between the lips. Blowing makes the blades slap together very fast. The sound is reedy and focused, with a strong band of overtones around 1,400 Hz according to the HyperPhysics formant table, and it cuts through a full orchestra. That clear sound is one reason why the oboe usually gives the A that the whole orchestra tunes to, a habit that is about 300 years old.

The bassoon is the bass of the woodwinds. Its double reed sits on the end of a curved metal pipe called the bocal, and its long wooden tube is folded back on itself so that a player can hold it. Its lowest note is B♭1, about 58 Hz. The contrabassoon goes an octave lower still.

Clarinet: one reed and a surprise

The clarinet has a single reed fixed to a mouthpiece. Its invention is credited to Johann Christoph Denner of Nuremberg, sometime between about 1690 and 1700. The clarinet behaves differently from the other woodwinds. Its narrow cylindrical tube, closed at one end by the reed, acts like a pipe closed at one end. Such a pipe favours odd-numbered harmonics, so when a clarinettist presses the register key, the note jumps a twelfth (an octave plus a fifth), not an octave as on the flute and oboe. The lowest register has a dark, hollow sound for the same reason.

The usual clarinet is pitched in B♭. When it reads a written C, it sounds the B♭ a whole step lower. Such instruments are called transposing instruments, and the conductor’s score shows their parts as they are written, not as they sound. A full orchestra usually has two to four players of each kind of woodwind.