A wind instrument
is a musical instrument
that contains some type of resonator
(usually a tube), in which a column of air is set into vibration by the player blowing into (or over) a mouthpiece
set at the end of the resonator. The pitch of the vibration is determined by the length of the tube and by manual modifications of the effective length of the vibrating column of air.
Methods for obtaining different notes
- Changing the length of the vibrating air column, by changing the effective length of the tube through opening or closing holes in the side of the tube. This can be done by covering the holes with fingers or pressing a key which then closes the hole. This method is used in nearly all woodwind instruments.
- Changing the length of the vibrating air column, by changing the length of the tube, through engaging valves (see rotary valve, piston valve) which route the air through additional tubing, thereby increasing overall tube length, thereby lowering the fundamental pitch. This method is used on nearly all brass instruments.
- Changing the length of the vibrating air column, by lengthening and/or shortening the tube using a sliding mechanism. This method is used on the trombone and the slide whistle.
- Making the column of air vibrate at different harmonics, without changing the length of the column of air (see harmonic series).
All wind instruments use a combination of the first or second or third and the fourth method to extend their register.
Types of wind instruments
Wind instruments fall into one of the following categories:
Although brass instruments were originally made of brass and woodwind instruments have traditionally been made of wood, the material used to make the body of the instrument is not always a reliable guide to its family type. A more accurate way to determine whether an instrument is brass or woodwind is to examine how the player produces sound. In brass instruments, the player's lips vibrate, causing the air within the instrument to vibrate. In woodwind instruments the player either:
- causes a reed to vibrate, which agitates the column of air (as in a clarinet, oboe or duduk)
- blows against an edge or fipple (as in a recorder), or
- blows across the edge of an open hole (as in a flute).
For example, the saxophone is typically made of brass, but is classified as a woodwind instrument due to the method of vibrating the air column (by using a reed).
On the other hand, the wooden cornett (not to be confused with the cornet, which is made of brass) and the serpent are both made of wood (or plastic tubing, in the case of modern serpents), but belong to the family of brass instruments because the vibrating is done by the player's lips.
In the Hornbostel-Sachs scheme of musical instrument classification, wind instruments are classed as aerophones.
The bell of a wind instrument is the round, flared opening opposite the mouthpiece. It is found on horns, trumpets and many other kinds of instruments. On brass instruments, the coustical coupling from the bore to the outside air occurs at the bell for all notes, and the shape of the bell optimizes this coupling. On woodwinds, most notes vent at the uppermost open tone holes; only the lowest notes of each register vent fully or partly at the bell, and the bell's function in this case is to improve the consistency in tone between these notes and the others.