 Woodwind instruments are not necessarily made of wood. The clarinet and oboe are made of wood, and use reeds to create air vibrations. They consist basically of a tube, with a series of holes that can be closed. Air is blown into the tube across a flexible reed. This makes the air inside the tube vibrate and give out a note. The pitch of the note depends on the length of the tube, a shorter tube giving a higher note. Blowing harder makes the sound louder. In the case of a flute or recorder, air is blown into an opening in one side of the tube to produce the vibrating air column. |
PADS AND KEYS In a short and simple woodwind instrument like the recorder, fingers can easily cover all the holes directly. Several woodwinds have holes that are larger than normal fingers, requiring the fingers to press on pads to cover the holes. Sprung keys attached to pads are used to cover holes cannot be reached by the fingers. |
SOUND FUNDAMENTALS A cylindrical air column with both ends open will vibrate with a fundamental mode such that the air column length is one half the wavelength of the sound wave. Each end of the column must be an antinode for the air motion since the ends are open to the atmosphere and cannot produce significant pressure changes. For the fundamental mode, there is one node at the center. |
ALL HOLES COVERED Covering all seven holes in a recorder makes the air in the whole tube vibrate, producing the note middle C. |
FIRST THREE HOLES COVERED Covering these effectively shortens the vibrating air column to two-thirds of the recorder, giving the higher note G. |
SINGLE-REED WOODWINDS  In the clarinet and saxophone, the mouthpiece contains a single reed that vibrates to set the air column inside the instrument vibrating. The clarinet consists of an approximate closed cylinder, and this makes clarinet acoustics quite different from the other woodwind instruments. The closed end is constrained to be a node of the wave and the open end is of course an antinode. This makes the fundamental mode such that the wavelength is four times the length of the air column. |
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DOUBLE-REED WOODWINDS The oboe and bassoon have a mouthpiece made of a double reed that vibrates to set the air column inside the instrument vibrating. The oboe has an unmistakable mournful tone. Its wooden tube is distinguished by a conical bore expanding at the end into a flaring bell. The bass member of this family, the bassoon, has a long conical tube that doubles back on itself. |
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EDGE-BLOWN WOODWINDS In the flute and recorder, the player blows air over an edge in the mouthpiece. This sets the air column inside the instrument vibrating.The modern flute is about 26 inches in length with an inside diameter of about 3/4", open at one end . The flute has a series of 16 openings in the tube wall, 11 of which can be closed directly by seven fingers and one by the left thumb. The four additional openings can be opened or closed by means of suitably arranged keys. |
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| One advantage of the flute over the recorder is that the player has direct control over the angle at which the air from the lips strikes the mouthpiece opening. Rolling in or out with the lips relative to the edge gives the player a greater range of volume and expression. This direct access to the edge also permits the player to make small fine tuning adjustments. |
