Aerophone
An
aerophone is any
musical instrument which produces
sound primarily by causing a body of air to vibrate, without the use of strings or
membranes, and without the vibration of the instrument itself adding considerably to the sound. It is one of the four main classes (class 4) of instruments in the original
Hornbostel-Sachs scheme of
musical instrument classification.
Hornbostel-Sachs divides aerophones by whether vibrating air is contained in the instrument itself or not.
The first class (
41) includes instruments where the vibrating air is
not contained by the instrument itself, such as the
bullroarer. Such instruments are called
free aerophones. This class includes
free reed instruments, such as the
harmonica, but also many instruments unlikely to be called wind instruments at all by most people, such as
sirens and
whips.
The second class (
42) includes instruments where the vibrating air
is contained by the instrument. This class includes almost all the instruments generally called
wind instruments in the west, such as the
flute, the
oboe and the
trumpet.
Additionally, very loud sounds can be made by explosions directed into, or being detonated inside of resonant cavities. Instruments such as the calliope (and steam whistle), as well as the
pyrophone might thus be considered as class 42 instruments, despite the fact that the "wind" or "air" may be steam or an air-fuel mixture.
