An aerophone is any musical instrument

Musical instrument

A musical instrument is a device created or adapted for the purpose of making musical sounds. In principle, any object that produces sound can serve as a musical instrument—it is through purpose that the object becomes a musical instrument. The history of musical instruments dates back to the...

 which produces sound

Sound

Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

 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 of instruments in the original Hornbostel-Sachs

Hornbostel-Sachs

Hornbostel–Sachs is a system of musical instrument classification devised by Erich Moritz von Hornbostel and Curt Sachs, and first published in the Zeitschrift für Ethnologie in 1914. An English translation was published in the Galpin Society Journal in 1961...

 scheme of musical instrument classification

Musical instrument classification

At various times, and in various cultures, various schemes of musical instrument classification have been used.The most commonly used system in use in the west today divides instruments into string instruments, wind instruments and percussion instruments...

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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

Bullroarer (music)

The bullroarer, rhombus, or turndun, is an ancient ritual musical instrument and a device historically used for communicating over greatly-extended distances. It dates to the Paleolithic period, being found in Ukraine dating from 17,000 BC...

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Such instruments are called free aerophones. This class includes free reed instruments, such as the harmonica

Harmonica

The harmonica, also called harp, French harp, blues harp, and mouth organ, is a free reed wind instrument used primarily in blues and American folk music, jazz, country, and rock and roll. It is played by blowing air into it or drawing air out by placing lips over individual holes or multiple holes...

, but also many instruments unlikely to be called wind instruments at all by most people, such as siren

Siren (noisemaker)

A siren is a loud noise making device. Most modern ones are civil defense or air raid sirens, tornado sirens, or the sirens on emergency service vehicles such as ambulances, police cars and fire trucks. There are two general types: pneumatic and electronic....

s and whips

Whip (instrument)

In music, a whip or slapstick is a percussion instrument consisting of two wooden boards joined by a hinge at one end. When the boards are brought together rapidly, the sound is reminiscent of the crack of a whip. It is often used in modern orchestras, bands, and percussion ensembles.There are...

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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 instrument

Wind instrument

A wind instrument is a musical instrument that contains some type of resonator , in which a column of air is set into vibration by the player blowing into 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...

s - including the didgeridoo

Didgeridoo

The didgeridoo is a wind instrument developed by Indigenous Australians of northern Australia around 1,500 years ago and still in widespread usage today both in Australia and around the world. It is sometimes described as a natural wooden trumpet or "drone pipe"...

, brass instruments in the west, such as the trumpet

Trumpet

The trumpet is the musical instrument with the highest register in the brass family. Trumpets are among the oldest musical instruments, dating back to at least 1500 BCE. They are played by blowing air through closed lips, producing a "buzzing" sound which starts a standing wave vibration in the air...

, the french horn, and the trombone

Trombone

The trombone is a musical instrument in the brass family. Like all brass instruments, sound is produced when the player’s vibrating lips cause the air column inside the instrument to vibrate...

, and woodwind instruments such as the sheng

Sheng (instrument)

The Chinese sheng is a mouth-blown free reed instrument consisting of vertical pipes.Traditionally, the sheng has been used as an accompaniment instrument for solo suona or dizi performances. It is one of the main instruments in kunqu and some other forms of Chinese opera...

, the oboe

Oboe

The oboe is a double reed musical instrument of the woodwind family. In English, prior to 1770, the instrument was called "hautbois" , "hoboy", or "French hoboy". The spelling "oboe" was adopted into English ca...

, and the clarinet

Clarinet

The clarinet is a musical instrument of woodwind type. The name derives from adding the suffix -et to the Italian word clarino , as the first clarinets had a strident tone similar to that of a trumpet. The instrument has an approximately cylindrical bore, and uses a single reed...

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Additionally, very loud sounds can be made by explosions directed into, or being detonated inside of resonant cavities. Instruments such as the calliope

Calliope (music)

A calliope is a musical instrument that produces sound by sending a gas, originally steam or more recently compressed air, through large whistles, originally locomotive whistles....

 (and steam whistle), as well as the pyrophone

Pyrophone

A pyrophone, also known as a "fire/explosion organ" or "fire/explosion calliope" is a musical instrument in which notes are sounded by explosions, or similar forms of rapid combustion, rapid heating, or the like.-Related musical instruments:...

might thus be considered as class 42 instruments, despite the fact that the "wind" or "air" may be steam or an air-fuel mixture.