Musical instruments are almost universal components of human culture: archaeology has revealed pipes and whistles in the Paleolithic Period and clay drums and shell trumpets in the Neolithic Period. It has been firmly established that the ancient city cultures of Mesopotamia, the Mediterranean, India, East Asia, and the Americas all possessed diverse and well-developed assortments of musical instruments, indicating that a long previous development must have existed. As to the origin of musical instruments, however, there can be only conjecture. Some scholars have speculated that the first instruments were derived from such utilitarian objects as cooking pots (drums) and hunting bows (musical bows); others have argued that instruments of music might well have preceded pots and bows; while in the myths of cultures throughout the world the origin of music has frequently been attributed to the gods, especially in areas where music seems to have been regarded as an essential component of the ritual believed necessary for spiritual survival.

Whatever their origin, the further development of the enormously varied instruments of the world has been dependent on the interplay of four factors: available material, technological skills, mythic and symbolic preoccupations, and patterns of trade and migration. Thus, residents of Arctic regions use bone, skin, and stone to construct instruments; residents of the tropics have wood, bamboo, and reed available; while societies with access to metals and the requisite technology are able to utilize these malleable materials in a variety of ways. Myth and symbolism play an equally important role. Herding societies, for example, which may depend on a particular species of animal not only economically but also spiritually, often develop instruments that look or sound like the animal or prefer instruments made of bone and hide rather than stone and wood, even when all the materials are available. Finally, patterns of human trade and migration have for many centuries swept musicians and their instruments across seas and continents, resulting in constant flux, change, and cross-fertilization and adaptation.

The sound (musical sound) produced by an instrument can be affected by many factors, including the material from which the instrument is made, its size and shape, and the way that it is played. For example, a stringed instrument may be struck, plucked, or bowed, each method producing a distinctive sound. A wooden instrument struck by a beater sounds markedly different from a metal instrument, even if the two instruments are otherwise identical. On the other hand, a flute made of metal does not produce a substantially different sound from one made of wood, for in this case the vibrations are in the column of air in the instrument. The characteristic timbre of wind instruments depends on other factors, notably the length and shape of the tube. The length of the tube not only determines the pitch but also affects the timbre: the piccolo, being half the size of the flute, has a shriller sound. The shape of the tube determines the presence or absence of the “upper partials” (harmonic or nonharmonic overtones (overtone)), which give colour to the single note. (For more on the science of sound, see acoustics.)

Musical instruments have been used since earliest times for a variety of purposes, ranging from the entertainment of concert audiences to the accompaniment of dances, rituals (ritual), work, and medicine. The use of instruments for religious ceremonies has continued down to the present day, though at various times they have been suspect because of their secular associations. The many references to instruments in the Old Testament are evidence of the fact that they played an important part in Jewish worship until for doctrinal reasons they were excluded. It is also clear that the early Christians in the eastern Mediterranean used instruments in their services, since the practice was severely condemned by ecclesiastics, who insisted that the references to instruments in the Psalms were to be interpreted symbolically. Although instruments continue to be banned in Islamic mosques (but not in religious processions or Sufi ritual) and in the traditional Eastern Orthodox church, they play important roles in the ritual of most other societies. For example, Buddhist cultures are rich in instruments, particularly bells and drums (and in the Tibet Autonomous Region of China, wind instruments as well).

Belief in the magical properties of instruments is found in many societies. The Jewish (Judaism) shofar (a ram's horn), which is still blown on Rosh Hashana (New Year) and Yom Kippur (Day of Atonement), must be heard by the congregation. The power of the shofar is illustrated by the story of Joshua at the siege of Jericho: when the priests blew their shofars seven times, the walls of the city fell flat. In India, according to legend, when the deity Krishna played the flute, the rivers stopped flowing and the birds came down to listen. The birds are said to have done the same in 14th-century Italy when the composer Francesco Landini (Landini, Francesco) played his organetto, or portative organ. In China, instruments were identified with the points of the compass, with the seasons, and with natural phenomena. The Melanesian bamboo flute was a charm for rebirth.

Many of the instruments used in medieval Europe came from western Asia, and they have retained some of their original symbolism. For example, trumpets (trumpet), long associated with military operations, had a ceremonial function in the establishment of European kings and nobles and were, in fact, regarded as a sign of nobility. In the later Middle Ages and for long afterward, they were associated with kettledrums (kettledrum) (known originally as nakers, after their Arab name, naqqārah), which were often played on horseback, as they still are in some mounted regiments. Trumpet fanfares, heard on ceremonial occasions in the modern world, are a survival of medieval practice.

The stretched string of a bow can produce several pitches when it is beaten, and the string can be stopped at points along its length to produce varied sounds. In addition, a resonator such as a pot or gourd is often used to increase the volume of the sound. The player's mouth can add variety to both volume and pitch. A tube of bamboo can become musical when it is struck on the ground, and a set of different-sized tubes can produce a melodic and rhythmic ensemble. Lifting strips of the bark from a tube and adding bridges under the strips creates a melodic zither, for which each strip produces a separate pitch. The sound can be enhanced by placing one end of the tube in a resonator, whether a gourd or a tin can. In sum, the complexity of music depends less on technology than on human imagination.

The first step in the building of any instrument is the selection and preparation of material. Wood used for wind or stringed instruments needs to be seasoned, as do the reeds used in oboes, clarinets, saxophones, and related instruments. Metals, which are widely used for strings, bells, cymbals, gongs, trumpets, and horns, must be manufactured and cast—often originally by secret processes. Next, the construction and tuning (tuning and temperament) of all instruments require skill and craftsmanship: the piercing of a tube to a uniform or expanding width, the flaring of the bell of a wind instrument to increase sonority, the measurement of the bars of a saron (for the Javanese gamelan) or of a glockenspiel, the curvature of the back of a lute or ʿūd, the internal and external structure of the body of a violin, a koto, or even a shakuhachi. All of these involve accurate workmanship from experts in wood and metal and, in many instances, a knowledge of the mathematics of sound.

The mathematical basis of accurate tuning systems has been the subject of philosophical and scientific speculation since ancient times; nevertheless, no single system has been deemed perfect (see also tuning and temperament). All practical tuning systems involve a series of compromises, a fact that instrument makers have known for centuries.

The instrument maker's skill, like that of the cabinetmaker and the silversmith, was developed by long practice, and the principles that determine both tone and intonation were discovered by trial and error. The growth of instrumental playing in 16th-century Europe stimulated the production of instruments to be used not merely for ceremonial and official entertainment but also for social occasions and private pleasure. From this time, records began to be kept of the names of makers, many of whom established family businesses that lasted for several generations. These include, for example, Andrea Amati (Amati Family) (16th century), a violin maker in Cremona, Italy; Hans Ruckers (Ruckers, Hans, The Elder) (late 16th century), a harpsichord maker in Antwerp, Belg.; and Johann Haas (1649–1723), a trumpet maker in Nürnberg (now in Germany). In all literate cultures there are known families or guilds of instrument makers, e.g., for the Middle Eastern ʿūd, South Asian sitar and vina, or Japanese tsuzumi drums. Around the world, instrument makers have long signed their products. Although similar respectful positions are held by instrument makers in cultures without a written record, their reputation is far less likely to spread beyond their particular time and place.

Instruments have been classified in various ways, some of which overlap. The Chinese (arts, East Asian) divide them according to the material of which they are made—as, for example, stone, wood, silk, and metal. Writers in the Greco-Roman world distinguished three main types of instruments: wind, stringed, and percussion. This classification was retained in the Middle Ages and persisted for several centuries: it is the one preferred by some writers, with the addition of electronic instruments, at the present day. Some 16th-century writers excluded certain instruments from this classification; the musical theorist Lodovico Zacconi (Zacconi, Lodovico) went so far as to exclude all percussion instruments and established a fourfold division of his own—wind, keyed, bowed, and plucked.

Classification and Examples of Some Musical InstrumentsA different fourfold classification was accepted by Hindus (Hinduism) at least as early as the 1st century BC: they recognized stringed instruments, wind instruments, percussion instruments of wood or metal, and percussion instruments with skin heads (i.e., drums). This ancient system—based on the material producing sound—was adopted by the Belgian instrument maker and acoustician Victor-Charles Mahillon (Mahillon, Victor-Charles), who named his four main classes autophones, or instruments made of a sonorous material that vibrates to produce sound (e.g., bells, rattles); membranophones (membranophone), in which a stretched skin is caused to vibrate (e.g., drums); aerophones (aerophone), in which the sound is produced by a vibrating column of air (wind instruments); and chordophones (chordophone), or stringed instruments. In their highly influential studies of musical instruments, the Austrian musicologist Erich von Hornbostel (Hornbostel, Erich Moritz von) and his German colleague Curt Sachs (Sachs, Curt) accepted and expanded Mahillon's basic division, creating the classification now used in most systematic studies of instruments. The name idiophones (idiophone) was substituted for autophones, and each class was subdivided according to a method similar to that used by botanists. A fifth class, electrophones (electrophone), in which vibration is produced by oscillating electric circuits, was added later. The Table (Classification and Examples of Some Musical Instruments) gives examples of instruments that fall within the various categories.

It must be understood that the Sachs-Hornbostel system was created for the purpose of bringing order to the massive collections of musical instruments in ethnographic museums. It is directly analogous to the various book classification systems of libraries and, like them, is arbitrary. Musicians themselves generally think of instruments in terms of their technological features and playing method. To them, therefore, it is logical to group keyboard instruments together, ignoring the fact that in the Sachs-Hornbostel system such instruments fit into several categories.

The development of musical instruments among ancient high civilizations in Asia, North Africa, and the Mediterranean appears to have emphasized stringed instruments. In Central and South America, wind and struck instruments seem to have been most important. It is not always easy to say whether instruments are indigenous to a particular area, however, since their cultivation may well have spread from one country to another through trade or migration. Nevertheless, it is known that the harp was used from early times in Mesopotamia, Egypt, and India and was imported into China after the end of the 4th century AD. In Greece it was regarded as a foreign instrument: the standard plucked instrument was the lyre, known in its fully developed form as the kithara (or cithara). Apart from the trumpet, the only wind instrument in normal use in Greece was the aulos, a double-reed instrument akin to the modern oboe. The Egyptians used wind instruments not only with double reeds but also with single reeds and thus may be said to have anticipated the clarinet. Peculiar to China was the sheng, or mouth organ; the Chinese also used as an artistic instrument the panpipes ( xiao), which in Greece had a recreational function.

Drum ensembles have achieved extraordinary sophistication in Africa, and the small hand-beaten drum is of great musical significance in western Asia and India. The native cultures of the Americas have always made extensive use of drums, as well as other struck and shaken instruments. In Southeast Asia and parts of Africa, xylophones and, since the introduction of metals, their cousins the metallophones play significant roles. Europe, however, has not placed great emphasis on drums and other percussion instruments. (See also percussion instrument.)

The European fiddle existed in various forms: by the 16th century these had settled down into two distinct types—the viol, known in Italy as viola da gamba (leg fiddle), and the violin, or viola da braccio (arm fiddle). The viol has a flat back, sloping shoulders, and six or seven strings; the violin has a rounded back, rounded shoulders, and four strings. The viol, unlike the violin, has frets—pieces of gut wound at intervals around the fingerboard—which make every stopped note (i.e., the string being pressed by the finger to produce a higher pitch) sound like an open (unstopped) string. The violin, being the smallest member of the family, came to be known by the diminutive violino: the tenor of the family was called simply viola, while the bass acquired the name violoncello, a diminutive of violone (“big fiddle”). (See also stringed instrument.)

Of all instruments, the organ showed the most remarkable development from the early Middle Ages to the 17th century. Originally, sound was admitted to the pipes by withdrawing sliders or depressing levers. Both of these methods were clumsy: they gave way to a reduction in the size of the levers, which eventually could be depressed by the fingers, while the larger pipes were controlled by pedals. A further development was to separate the various rows of pipes, so that each row could be brought into action or suppressed by means of a draw stop. Once a manageable keyboard had been produced, it could be applied to the portable organ, carried by the player, which was already in use by the 12th century. Scientific experiments with the monochord, a stretched string that could be divided into various lengths by means of a metal tangent, were followed by the construction of an instrument with a whole range of strings and a keyboard similar to that of the organ—the clavichord. A similar adaptation of the plucking of stringed instruments led to the harpsichord, the ingenious mechanism of which had been perfected by the 16th century. It is curious that a similar method was not applied to the dulcimer, which was struck with hammers, until the early 18th century, when the Italian maker Bartolomeo Cristofori (Cristofori, Bartolomeo) constructed the first pianoforte (piano), so-called because, unlike the harpsichord, it could vary the tone from soft (piano) to loud (forte). (See also keyboard instrument.)

Trumpets and horns were used in most areas of Eurasia for ceremonial and military purposes. They remained relatively unchanged until the early 19th century, when valves were added to European instruments. This modification also led to the creation of new types. A pioneer in the field was the Belgian instrument maker Antoine-Joseph Sax (Sax, Antoine-Joseph), who in 1845 built a family of valved instruments called saxhorns (saxhorn), using the bugle as the basis for his invention. Similar instruments were widely adopted in military and brass bands, but only the bass, under the name bass tuba, became a normal member of the orchestra. Sax also invented the saxophone, a single-reed instrument like the clarinet but with a conical tube. This, too, was made in various sizes, which came to be used both in military bands and in jazz ensembles. The saxophone never became a normal member of the symphony orchestra, but the alto and the tenor have been used by art-music composers, largely as solo instruments, and occasionally a complete quartet of four different sizes has appeared in an orchestral work. (See also wind instrument.)

The variety of musical ensembles used throughout the world is vast and beyond description, but the following principles apply nearly everywhere. Outdoor music, which is often ceremonial, most frequently involves the use of loud wind instruments and drums. Indoor music, which is more often intended for passive listening, emphasizes such quieter instruments as bowed and plucked strings and flutes.

Water power, clockwork, steam, and electricity have all been used at various times to power musical instruments, enabling them to produce sound automatically. Examples include church bells, automatic organs, musical clocks, automatic pianos and harpsichords, music boxes, calliopes, and even automatic orchestras. Most of the impetus behind this phenomenon ceased with the development of the phonograph and other recording devices of the 20th century.

The development of electricity led not only to its use for mechanical purposes—for example, to control the key action and wind flow in the organ—but also as a means of amplification (e.g., in the vibraphone). With advances in electronics technology, players can now also make use of computers to generate and store tones and musical patterns. The growth of companies manufacturing electronic and digital instruments has been rapid, and the use of electronic equipment, such as sound synthesizers and recorders using analog or digital media, to produce and combine sound unrelated to the musical scale has become common.

Comprehensive information on diverse musical instruments is found in such authoritative reference sources as Don Michael Randel, The New Harvard Dictionary of Music, 4th ed. (2003); New Oxford History of Music, 10 vol. (1954–90), with various reprints and reissues of individual volumes (1976–97); Stanley Sadie (ed.), The New Grove Dictionary of Musical Instruments, 3 vol. (1984, reprinted 1997); Bruno Nettl et al. (eds.), The Garland Encyclopedia of World Music, 10 vol. (1998–2002); Q. David Bowers, Encyclopedia of Automatic Musical Instruments (1972); and Richard Dobson, A Dictionary of Electronic and Computer Music Technology: Instruments, Terms, Techniques (1992).History and evolution of musical instruments are studied in many well-illustrated works, including J. Peter Burkholder, Donald Jay Grout, and Claude V. Palisca, A History of Western Music, 7th ed. (2006); Giovanni Comotti, Music in Greek and Roman Culture (1989; originally published in Italian, 1979); Thomas J. Mathiesen, Apollo's Lyre: Greek Music and Music Theory in Antiquity and the Middle Ages (1999); David Munrow, Instruments of the Middle Ages and Renaissance (1976); Sibyl Marcuse, A Survey of Musical Instruments (1975); Anthony Baines (ed.), Musical Instruments Through the Ages, new ed. (1976); Robert Donington, Music and Its Instruments (1982); Curt Sachs, The History of Musical Instruments (1940, reprinted 1968); and Jeremy Montagu, The World of Medieval and Renaissance Musical Instruments (1976), The World of Baroque and Classical Musical Instruments (1979), and The World of Romantic & Modern Musical Instruments (1981).Physical properties of the instruments are addressed in Reinhold Banek and Jon Scoville, Sound Designs: A Handbook of Musical Instrument Building (1980, reissued 1995); Charles Ford (ed.), Making Musical Instruments: Strings and Keyboard (1979); Dennis Waring, Folk Instruments (1979, reprinted as Making Folk Instruments in Wood, 1982, and as Making Wood Folk Instruments, 1990); and Neville H. Fletcher and Thomas D. Rosing, The Physics of Musical Instruments, 2nd ed. (1998, reissued 2005).Exhibitions and collections are the source of useful and well-illustrated information. A selection of catalogs includes Phillip T. Young, The Look of Music: Rare Musical Instruments, 1500–1900 (1980); Laurence Libin, American Musical Instruments in The Metropolitan Museum of Art (1985); James M. Borders, European and American Wind and Percussion Instruments: Catalogue of the Stearns Collection of Musical Instruments, University of Michigan (1988); Clifford Bevan, Musical Instrument Collections in the British Isles (1990); and James Coover, Musical Instrument Collections: Catalogues and Cognate Literature (1981).Geographic and ethnic distribution of musical instruments is explored in Nicholas Bessaraboff, Ancient European Musical Instruments (1941, reissued 1964); Emanuel Winternitz, Musical Instruments of the Western World (1967); Jaap Kunst, Music in Java, 3rd ed., rev. by E.L. Heins, 2 vol. (1973; originally published in Dutch, 1934); William P. Malm, Japanese Music and Musical Instruments (1959, reissued 1990), and Music Cultures of the Pacific, the Near East, and Asia, 2nd ed. (1977); S. Bandyopadhyaya, Musical Instruments of India (1980); Marie-Thérèse Brincard (ed.), Sounding Forms: African Musical Instruments (1989); Mary Remnant, Musical Instruments of the West (1978); and Emanuel Winternitz, Musical Instruments and Their Symbolism in Western Art (1967, reissued 1979).The process of arranging music for particular instruments and combinations of instruments is discussed in Howard Mayer Brown, Sixteenth-Century Instrumentation: The Music for the Florentine Intermedii (1973); Claude V. Palisca, Baroque Music, 3rd ed. (1991), surveying the seminal period in the development of concerted music; Adam Carse, The History of Orchestration (1925, reissued 1964); Hector Berlioz, Treatise on Instrumentation, rev. and enlarged by Richard Strauss (1948; originally published in French, 1844); Nicolas Rimsky-Korsakow (Nikolay Rimsky-Korsakov), Principles of Orchestration, trans. from Russian (1923, reissued 1964); Michael Hurd, The Orchestra (1980); Madeau Stewart, The Music Lover's Guide to the Instruments of the Orchestra (1980); Joan Peyser (ed.), The Orchestra: Origins and Transformations (1986); and Mark C. Gridley and David Cutler, Jazz Styles: History & Analysis, 8th ed. (2003).Current developments and research in the field are reflected in the articles of such special periodicals as The Galpin Society Journal (annual); Journal of the American Musical Instrument Society (annual); The Musical Quarterly; Early Music (quarterly); Ethno-musicology (3/yr.); and Asian Music (semiannual).Sir Jack Allan Westrup Theodore C. Grame Ed.