) 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. It is the most widely used system for classifying musical instruments
(people who study musical instruments).
The system is based on one devised in the late 19th century by Victor-Charles Mahillon, the curator of Brussels Conservatory's musical instrument collection. Mahillon divided instruments into four broad categories according to the nature of the sound-producing material (air column, string, membrane, the body of the instrument). He took these categories from the Natya Sastra, a roughly two-thousand-year-old Indian theoretical treatise on music and dramaturgy. Mahillon's system was limited, for the most part, to western instruments used in classical music. The Sachs-Hornbostel system is an expansion on Mahillon's in that it is possible to classify any instrument from any culture with it.
Basis of the system
Formally, Hornbostel-Sachs is based on the Dewey Decimal classification
. It has four top level classifications, with several levels below those, adding up to over 300 basic categories in all. The top two levels of the scheme, with explanations, are shown below:
- 1. Idiophones - sound is primarily produced by the actual body of the instrument vibrating, rather than a string, membrane, or column of air. In essence, this group includes all percussion instruments apart from drums, as well as some other instruments.
- 11. Struck idiophones - idiophones set in vibration by being struck, for example cymbals or xylophones.
- 111 = directly;
- 1112 = percussion idiophones (struck-upon)
- 11124 = percussion vessels
- 111242 = bells
- 1112422 sets of bells
- 11124222 sets of hanging bells
- 11124222 sets of hanging bells with internal strikers. Typically decimal points are inserted as follows: 111.242.222
- 112 = indirectly.
- 12. Plucked idiophones (lamellophones) - idiophones set in vibration by being plucked, for example the Jew's harp or thumb piano.
- 121 = in frame;
- 122 = in board or comb form.
- 13. Friction idiophones - idiophones which are rubbed, for example the nail violin, a bowed instrument with solid pieces of metal or wood rather than strings.
- 131 = with sticks;
- 132 = with plaques;
- 133 = with vessels.
- 14. Blown idiophones - idiophones set in vibration by the movement of air, for example the Aeolsklavier, an instrument consisting of several pieces of wood which vibrate when air is blown onto them by a set of bellows.
- 141 = with sticks;
- 142 = with plaques.
- 2. Membranophones - sound is primarily produced by the vibration of a tightly stretched membrane. This group includes all drums and kazoos.
- 21. Struck drums - instruments which have a struck membrane. This includes most types of drum, such as the timpani and snare drum.
- 22. Plucked drums - these are drums with a knotted string attached to the membrane. When the string is plucked, it passes the vibration on to the membrane, which vibrates to give the sound. Some kinds of Indian drums are like this. Some commentators believe that instruments in this class ought instead to be regarded as chordophones (see below).
- 23. Friction drums - drums which are rubbed, either with the hand, a stick, or something else, rather than being struck.
- 24. Singing membranes - this group includes kazoos, instruments which do not produce noise of their own, but modify other noises by way of a vibrating membrane.
- 3. Chordophones - sound is primarily produced by the vibration of a string or strings. This group includes all instruments generally called string instruments in the west, as well as many (but not all) keyboard instruments, such as pianos and harpsichords.
- 31. Simple chordophones - instruments which are in essence simply a string or strings and a string bearer. These instruments may have a resonator box, but removing it should not render the instrument unplayable (although it may result in quite a different sound being produced). They include the piano therefore, as well as other kinds of zithers such as the koto, and musical bows.
- 32. Composite chordophones - acoustic and electro-acoustic instruments which have a resonator as an integral part of the instrument, and solid-body electric chordophones. This includes most western string instruments, including lutes such as violins and guitars, and harps.
- 4. Aerophones - sound is primarily produced by vibrating air. The instrument itself does not vibrate, and there are no vibrating strings or membranes.
- 41. Free aerophones - instruments where the vibrating air is not enclosed by the instrument itself, for example sirens, or the bullroarer.
- 42. Wind instruments - instruments where the vibrating air is enclosed by the instrument. This group includes most of the instruments called wind instruments in the west, such as the flute or French horn, as well as many other kinds of instruments such as conch shells.
- 5. Electrophones -
- 51. Instruments having electric action (e.g. pipe organ with electrically controlled solenoid air valves);
- 52. Instruments having electrical amplification, such as the Neo-Bechstein piano of 1931, which had 18 microphones built into it;
- 53. Radioelectric instruments: instruments in which sound is produced by electrical means.
The fifth top-level group, electrophones category was added by Sachs in 1940, to describe instruments involving electricity. Sachs broke down his 5th category into 3 subcategories: 51=electrically actuated acoustic instruments; 52=electrically amplified acoustic instruments; 53= instruments in which make sound primarily by way of electrically driven oscillators, such as theremins or synthesizers, which he called radioelectric instruments. Francis William Galpin provided such a group in his own classification system, which is closer to Mahillon than Sachs-Hornbostel. For example, in Galpin's 1937 book A Textbook of European Musical Instruments, he lists electrophones with three second-level divisions for sound generation ("by oscillation," "electro-magnetic," and "electro-static"), as well as third-level and fourth-level categories based on the control method. Sachs himself proposed subcategories 51, 52, and 53, on pages 447-467 of his 1940 book The History of Musical Instruments. However, the original 1914 version of the system did not acknowledge the existence of his 5th category.
Present-day ethnomusicologists, such as Margaret Kartomi (page 173), and Ellingson (PhD dissertation, 1979, p. 544) suggest that, in keeping with the spirit of the original Hornbostel Sachs classification scheme, of categorization by what first produces the initial sound in the instrument, that only subcategory 53 should remain in the electrophones category. Thus it has been more recently proposed that, for example, the pipe organ (even if it uses electric key action to control solenoid valves) remain in the aerophones category, and that the electric guitar remain in the chordophones category, etc..
Application of the system
Beyond these top two groups are several further levels of classification, so that the xylophone
, for example, is in the group labelled 111.212 (periods are usually added after every third digit to make long numbers easier to read). A long classification number does not necessarily indicate the instrument is a complicated one. The bugle
for instance, has the classification number 423.121.22, even though it is generally regarded as a relatively simple instrument (it is basically a bent conical tube which you blow down like a trumpet
, but it does not have valves or finger-holes). The numbers in the bugle's classification indicate the following:
- 4 - an aerophone
- 42 - the vibrating air is enclosed within the instrument
- 423 - the player's lips cause the air to vibrate directly (as opposed to an instrument with a reed like a clarinet, or an edge-blown instrument, like a flute)
- 423.1 - the player's lips are the only means of changing the instrument's pitch (that is, there are no valves as on a trumpet)
- 423.12 - the instrument is tubular, rather than being a conch-type instrument
- 423.121 - the player blows into the end of the tube, as opposed to the side of the tube
- 423.121.2 - the tube is bent or folded, as opposed to straight
- 423.121.22 - the instrument has a mouthpiece
423.121.22 does not uniquely identify the bugle, but rather identifies the bugle as a certain kind of instrument which has much in common with other instruments in the same class. Another instrument classified as 423.121.22 is the bronze lur, an instrument dating back to the Bronze Age.
Suffixes and composite instruments
After the number described above, a number of suffixes may be appended. An 8
indicates that the instrument has a keyboard attached, while a 9
indicates the instrument is mechanically driven. In addition to these, there are a number of suffixes unique to each of the top-level groups indicating details not considered crucial to the fundamental nature of the instrument. In the membranophone class, for instance, suffixes can indicate whether the skin of a drum is glued, nailed or tied to its body; in the chordophone class, suffixes can indicate whether the strings are plucked with fingers or plectrum, or played with a bow.
There are ways to classify instruments with this system even if they have elements from more than one group. Such instruments may have particularly long classification numbers with colons and hyphens used as well as numbers. Hornbostel and Sachs themselves cite the case of a set of bagpipes where some of the pipes are single reed (like a clarinet) and others are double reed (like the oboe). A number of similar composite instruments exist.