General term for musical instruments that produce their sound by setting up vibrations in a body of air. Aerophones form one of the original four classes of instruments (along with idiophones, membranophones and chordophones) in the hierarchical classification devised by E.M. von Hornbostel and C. Sachs and published by them in Zeitschrift für Ethnologie in 1914 (Eng. trans. in GSJ, xiv, 1961, pp.3–29, repro. in Ethnomusicology: an Introduction, ed. H. Myers, London, 1992, pp.444–61). Their system, which draws on that devised by Victor-Charles Mahillon for the Royal Conservatory in Brussels and is widely used today, divides instruments into groups which employ air, strings, membranes or sonorous materials to produce sounds. Various scholars, including Galpin (Textbook of European Instruments, London, 1937) and Sachs (History of Musical Instruments, New York, 1940), have suggested adding electrophones to the system, but it has not yet been formally extended.
Aerophones are subdivided into ‘free aerophones’ (e.g. the bullroarer), in which vibrations are set up in a body of air unconfined by the structure of the instrument, and wind instruments where the air is enclosed inside a tube or vessel. The latter group includes those instruments where sound is produced by directing a stream of air against an edge (flutes and duct flutes), by the vibration of a reed, or by the vibration of the player’s lips. Each category is further subdivided according to the more detailed characteristics of an instrument. A numeric code, similar to the class marks of the Dewey decimal library classification system, indicates the structure and physical function of the instrument. The Hornbostel-Sachs classification (from the GSJ translation, with minor alterations) follows as an appendix to this article.
For further information on the classification of instruments in general see Instruments, classification of.
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4 Aerophones: the air itself is the vibrator in the primary sense |
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41 Free aerophones: the vibrating air is not confined by the instrument |
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411 Displacement free aerophones: the airstream meets a sharp edge, or a sharp edge is moved through the air. In either case a periodic displacement of air occurs to alternate flanks of the edge (whip, sword-blade) |
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412 Interruptive free aerophones: the airstream is interrupted periodically |
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412.1 Idiophonic interruptive aerophones or reeds: the airstream is directed against a lamella, setting it in periodic vibration to interrupt the stream intermittently. In this group also belong reeds with a ‘cover’, i.e. a tube in which the air vibrates only in a secondary sense, not producing the sound but simply adding roundness and timbre to the sound made by the reed’s vibration: generally recognizable by the absence of finger-holes (organ reed stops) |
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412.11 Concussion reeds: two lamellae make a gap which closes periodically during their vibration (a split grass-blade) |
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412.12 Percussion reeds: a single lamella strikes against a frame |
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412.121 Individual percussion reeds: found in British Columbia |
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412.122 Sets of percussion reeds (the earlier reed stops of organs) |
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412.13 Free reeds: the lamella vibrates through a closely fitting slot |
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412.131 (Individual) free reeds (single-note motor horn) |
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412.132 Sets of free reeds: NB in instruments like the Chinese sheng the finger-holes do not serve to modify the pitch and are therefore not equivalent to the finger-holes of other pipes (reed organ, mouth organ, accordion) |
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412.14 Ribbon reeds: the airstream is directed against the edge of a stretched band or ribbon. The acoustics of this process has not yet been studied – found in British Columbia |
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412.2 Non-idiophonic interruptive instruments: the interruptive agent is not a reed |
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412.21 Rotating aerophones: the interruptive agent rotates in its own plane (sirens) |
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412.22 Whirling aerophones: the interruptive agent turns on its axis (bullroarer, whirring disc, ventilating fan) |
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413 Plosive aerophones: the air is made to vibrate by a single density stimulus condensation shock (pop guns) |
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42 Wind instruments proper: the vibrating air is confined within the instrument itself |
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421 Edge instruments or flutes: a narrow stream of air is directed against an edge |
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421.1 Flutes without duct: the player creates a ribbon-shaped stream of air with his lips |
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421.11 End-blown flutes: the player blows against the sharp rim at the upper open end of a tube |
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421.111 (Single) end-blown flutes |
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421.111.1 Open single end-blown flutes: the lower end of the flute is open |
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421.111.11 Without finger-holes: found in Bengal |
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421.111.12 With finger-holes: found almost worldwide |
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421.111.2 Stopped single end-blown flutes: the lower end of the flute is closed |
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421.111.21 Without finger-holes (the bore of a key) |
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421.111.22 With finger-holes: found especially in New Guinea |
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421.112 Sets of end-blown flutes or panpipes: several end-blown flutes of different pitch are combined to form a single instrument |
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421.112.1 Open panpipes |
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421.112.11 Open (raft) panpipes: the pipes are tied together in the form of a board, or made by drilling tubes in a board – found in China |
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421.112.2 Open bundle (pan)pipes: the pipes are tied together in a round bundle – found in the Solomon Islands, New Britain, New Ireland and the Admiralty Islands |
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421.112.21 Stopped panpipes: found in Europe and South America |
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421.112.3 Mixed open and stopped panpipes: found in the Solomon Islands and South America |
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421.12 Side-blown flutes: the player blows against the sharp rim of a hole in the side of the tube |
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421.121 (Single) side-blown flutes |
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421.121.1 Open side-blown flutes |
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421.121.11 Without finger-holes: found in south-west Timor |
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421.121.12 With finger-holes (European flute) |
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421.121.2 Partly stopped side-blown flutes: the lower end of the tube is a natural node of the pipe pierced by a small hole – found in north-west Borneo |
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421.121.3 Stopped side-blown flutes |
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421.121.31 Without finger-holes |
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421.121.311 With fixed stopped lower end (apparently non-existent) |
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421.121 312 With adjustable stopped lower end (piston flutes) – found in Malacca [now West Malaysia] and New Guinea |
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421.121.32 With finger-holes: found in east Bengal and Malacca [now West Malaysia] |
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421.122 Sets of side-blown flutes |
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421.122.1 Sets of open side-blown flutes (chamber flute orum) |
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421.122.2 Sets of stopped side-blown flutes: found in north-west Brazil, among the Siusi |
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421.13 Vessel flutes (without distinct beak): the body of the pipe is not tubular but vessel-shaped – found in Brazil (Karaja) and the Lower Congo (Bafiote) |
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421.2 Flutes with duct, or duct flutes: a narrow duct directs the airstream against the sharp edge of a lateral orifice |
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421.21 Flutes with external duct: the duct is outside the wall of the flute; this group includes flutes with the duct chamfered in the wall under a ring-like sleeve and other similar arrangements |
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421.211 (Single) flutes with external duct |
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421.211.1 Open flutes with external duct |
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421.211.11 Without finger-holes: found in China and Borneo |
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421 211.12 With finger-holes: found in Indonesia |
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421.211.2 Partly stopped flutes with external duct: found in Malacca [now West Malaysia] |
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421.211.3 Stopped flutes with external duct |
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421.212 Sets of flutes with external duct: found in Tibet |
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421.22 Flutes with internal duct: the duct is inside the tube. This group includes flutes with the duct formed by an internal baffle (natural node, block of resin) and an exterior tied-on cover (cane, wood or hide) |
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421.221 (Single) flutes with internal duct |
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421.221.1 Open flutes with internal duct |
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421.221.11 Without finger-holes (European signalling whistle) |
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421.221.12 With finger-holes (recorder) |
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421.221.2 Partly stopped flute with internal duct: found in India and Indonesia |
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421.221.3 Stopped flutes with internal duct |
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421.221.31 Without finger-holes |
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421.221.311 With fixed stopped lower end (European signalling whistle) |
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421.221.312 With adjustable stopped lower end (piston pipes [swanee whistle]) |
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421.221.4 Vessel flutes with duct |
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421.221.41 Without finger-holes (zoomorphic pottery whistles) – found in Europe and Asia |
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421.221.42 With finger-holes (ocarina) |
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421.222 Sets of flutes with internal duct |
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421.222.1 Sets of open flutes with internal duct |
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421.222.11 Without finger-holes (open flue stops of the organ) |
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421.222.12 With finger-holes (double flageolet) |
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421.222.2 Sets of partly stopped flutes with internal duct (Rohrflöte stops of the organ) |
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421.222.3 Sets of stopped flutes with internal duct (stopped flue stops of the organ) |
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422 Reedpipes: the airstream has, through means of two lamellae placed at the head of the instrument, intermittent access to the column of air which is to be made to vibrate |
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422.1 Oboes: the pipe has a [double] reed of concussion lamellae (usually a flattened stem) |
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422.11 (Single) oboes |
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422.111 With cylindrical bore |
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422.111.1 Without finger-holes: found in British Columbia |
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422.111.2 With finger-holes (aulos, crumhorn) |
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422.112 With conical bore (European oboe) |
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422.12 Sets of oboes |
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422.121 With cylindrical bore (double aulos) |
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422.122 With conical bore: found in India |
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422.2 Clarinets: the pipe has a [single] ‘reed’ consisting of a percussion lamella |
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422.21 (Single) clarinets |
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422.211 With cylindrical bore |
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422.211.1 Without finger-holes: found in British Columbia |
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422.211.2 With finger-holes (European clarinet) |
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422.212 With conical bore (saxophone) |
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422.22 Sets of clarinets: found in Egypt (zummara) |
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422.3 Reedpipes with free reeds: the reed vibrates through [at] a closely fitted frame. There must be finger-holes, otherwise the instrument belongs to the free reeds 412.13 – found in South-east Asia |
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422.31 Single pipes with free reeds |
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422.32 Double pipes with free reeds |
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423 Trumpets: the airstream passes through the player’s vibrating lips, so gaining intermittent access to the air column which is to be made to vibrate |
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423.1 Natural trumpets: without extra devices to alter pitch |
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423.11 Conches: a conch shell serves as trumpet |
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423.111 End-blown |
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423.111.1 Without mouthpiece: found in India |
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423.111.2 With mouthpiece: found in Japan |
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423.112 Side-blown: found in Oceania |
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423.12 Tubular trumpets |
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423.121 End-blown trumpets: the mouth-hole faces the axis of the trumpet |
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423.121.1 End-blown straight trumpets: the tube is neither curved nor folded |
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423.121.11 Without mouthpiece (some alphorns) |
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423.121.12 With mouthpiece: found almost worldwide |
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423.121.2 End-blown horns: the tube is curved or folded |
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423.121.21 Without mouthpiece: found in Asia |
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423.121.22 With mouthpiece (lurs) |
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423.122 Side-blown trumpets: the mouth-hole is in the side of the tube |
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423.122.1 Side-blown straight trumpets: found in South America |
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423.122.2 Side-blown horns: found in Africa |
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423.2 Chromatic trumpets: with extra devices to modify the pitch |
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423.21 Trumpets with finger-holes (cornetti, key bugles) |
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423.22 Slide trumpets: the tube can be lengthened by extending a telescopic section of the instrument (European trombone) |
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423.23 Trumpets with valves: the tube is lengthened or shortened by connecting or disconnecting auxiliary lengths of tube – found in Europe |
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423.231 Valve bugles: the tube is conical throughout |
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423.232 Valve horns: the tube is predominantly conical |
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423.233 Valve trumpets: the tube is predominantly cylindrical |
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Suffixes for use with any division of this class: |
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6 with air reservoir |
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61 with rigid air reservoir |
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62 with flexible air reservoir |
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7 with finger-hole stopping |
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71 with keys |
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72 with Bandmechanik [presumably a perforated roll or ribbon] |
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8 with keyboard |
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9 with mechanical drive |
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Appendix reprinted from Hornbostel and Sachs, 1914 (by permission of Limbach Verlag, Berlin); Eng. trans., 1961/R |
HOWARD MAYER BROWN/FRANCES PALMER