A prepared piano is a piano which has had its sound altered by placing objects between or on the strings or on the hammers or dampers. The idea of altering an instrument’s timbre through the use of external objects has been applied to instruments other than the piano, such as the guitar. Although it is possible to prepare an upright piano, it is far easier, and far more common, on a grand piano.

A composer using prepared piano extensively was John Cage, who is often credited with inventing the instrument. He first prepared a piano when he was commissioned to write music for Bacchanale, a dance by Syvilla Fort in 1938. For some time previously, Cage had been writing exclusively for a percussion ensemble, but the hall where Fort’s dance was to be staged had no room for a percussion group. The only instrument available was a single grand piano.

After some consideration, Cage said that he realized it was possible to place in the hands of a single pianist the equivalent of an entire percussion orchestra. With just one musician, you can really do an unlimited number of things on the inside of the piano if you have at your disposal an exploded keyboard. Cage would often quip that by preparing a piano he left it in better condition than he found it.

In Cage’s use, the preparations are typically nuts, bolts and pieces of rubber to be lodged between and entwined around the strings. Some preparations make duller, more percussive sounds than usual, while others create sonorous bell-like tones. Additionally, the individual parts of a preparation like a nut loosely screwed onto a bolt will vibrate themselves, adding their own unique sound.

By placing the preparation between two of the strings on a note which has three strings assigned to it, it is possible to change the timbre of that note by depressing the soft pedal on the piano, which moves the hammers so they strike only two strings instead of all three. Other prepared piano sounds can be reminiscent of mbiras, marimbas, bells, wood blocks, Indonesian gamelan instruments, or many other sounds less easily defined.

American composer Chris Brown created a type of prepared electric piano, the Gazamba from the shell of a Wurlitzer electric piano. American composer Eric Glick Rieman has composed extensively for prepared Fender Rhodes pianos. Ross Bolleter has taken the idea into an innovative direction, exploring the use of ruined pianos, or pianos decayed by weather and time.

A gamelan is a musical ensemble from Indonesia, typically from the islands of Bali or Java, featuring a variety of instruments such as metallophones, xylophones, drums and gongs. The word comes from the Javanese word “gamel” meaning to strike or hammer, and the suffix “an”, which makes the root a collective noun.

The term refers more to the set of instruments than to the players of those instruments. A gamelan is a set of instruments as a distinct entity, built and tuned to stay together. Instruments from different gamelan are generally not interchangeable.

In Javanese mythology, the gamelan was created in AD 230. The god who ruled as king of all Java from a palace on Mount Lawu needed a signal to summon the gods, and thus invented the gong. For more complex messages, he invented two other Gongs, thus forming the basis of the original gamelan set.

The gamelan predates the Hindu-Buddhist culture that dominated Indonesia in its earliest records, and instead represents a native art form. In contrast to the Indian influence in other art forms, the only obvious Indian influence in gamelan music is in the Javanese style of singing.

In Indonesia, gamelan usually accompanies dance, puppet performances, or rituals and ceremonies. Typically players in the gamelan will be familiar with dance moves and poetry, while dancers are able to play in the ensemble. In wayang puppet performances, the puppeteer must have a thorough knowledge of gamelan, as he gives the cues for the music.

Gamelan’s role in rituals is so important that there is a Javanese saying that “It’s not official until the gong is hung.” Certain gamelans are associated with specific rituals, such as the Gamelan Sekaten, which is used in celebration of Muhammad’s birthday. In Bali, almost all religious rituals include gamelan performance. Gamelan is also used in the ceremonies of the Catholic church in Indonesia.

Certain pieces are designated for starting and ending performances or ceremonies. When a “leaving” piece is begun, the audience will know that the event is nearly finished and will begin to leave. Certain pieces are also believed to possess magic powers, and can be used to ward off evil spirits.

There is an increasing amount of gamelan outside Indonesia. There are even forms of gamelan that have originated outside Indonesia, such as American gamelan and Malay Gamelan in Malaysia.

There are also professional American gamelan ensembles. Gamelan Son of Lion is a group that focuses on newly composed music by both the members of the group and invited composers from around the world. Gamelan Kori Mas performs Balinese music on bamboo instruments in the San Francisco bay area.

The gudastviri is a droneless, double chantered, horn belled bagpipe played in the Caucasus region between Europe and Asia. The word comes from the words guda (bag) and stviri (whistling). In some regions, the instrument is called the chiboni, stviri, or tulumi.

It is made up of two parts, the first being a whole sheep or goat skin, or a sewed, rectangular leather bag (“guda”). The second is a yoked double chant pipe (“stviri”), terminating in a single horn bell, which makes the gudastviri a member of the hornpipe class of bagpipes.

The gudastviri is used for vocal accompaniment. A majority of recitative songs were performed with its accompaniment, in the region of Racha. The gudastviri player’s repertoire consists of historical, epic, satirical, comic, and lyrical verses, which are performed as one part songs. These songs are recitatives and it is the text, not the melody, that is the most important part of the performance.

Traditionally, only men play this instrument, and Rachian gudastviri players were strolling musicians, who were welcomed as guests at every family party or wedding. It was a profession that served as the main source of the player’s income. Gudastviri players often took part in the Georgian improvisation competition known as berikaoba, where they had to invent a witty epic, lyrical or comical poem accompanied with gudastviri music.

In the region of eastern Javakheti, gudastviri pipes are made of very young branches of a dog rose. One should possess special knowledge to design it. Jewelers are hired to make ornaments on the instrument. The gudastviri itself is nomally designed by the player. The player’s tastes and preferences determine where and how the ornaments should be attached.

A tromba marina or marine trumpet is a triangular bowed string instrument used in medieval and Renaissance Europe that was highly popular in the 15th century in England and survived into the 18th century. The tromba marina consists of a body and neck in the shape of a truncated cone resting on a triangular base. It is usually four to seven feet long and is a monochord, although some versions have sympathetically vibrating strings. It is played without stopping the string, but playing natural harmonics by lightly touching the string with the thumb at nodal points. Its name comes from its trumpetlike sound due to the unusual construction of the bridge.

During the time of Michael Praetorius in 1618, the length of the Trummscheit was 7′ 3″ and the three sides at the base measured 7″, tapering to 2″ at the neck. There was at first only one string, generally a D cello string. The heavy bow, similar to that of the cello, is used between the highest positions of the left hand at the nodal points and the nut of the head. In one catalogued example the frets are lettered A, D, F, A, D, F, G, A, B, C, D.

The body of the tromba marina is generally either three slats of wood joined in an elongated pyramid shape with a pegbox at the apex, or a body of three to six ribs, a frontal soundboard, and a distinguishable neck. In most cases the bottom end of the instrument is open. Some historical models use sound holes. The single string is tuned to the D three octaves below middle C. It attaches at the soundboard and passes over one foot of the bridge, leaving the other foot to vibrate freely on a plate of ivory or glass set into the soundboard creating a brassy buzz.

From its curiously irregular shape, the bridge is also known as the shoe. It is thick and high at the one side on which rests the string, and low and narrow at the other which is left loose so that it vibrates against the belly with every movement of the bow. A string called a guidon is tied around the playing string below the bridge and runs up to the pegbox where it is wrapped around a peg. The guidon adjusts the balance of the bridge by pulling the playing string.

The measurements of the tromba marina varied considerably, as did also the shape of the body and the number of strings. An octave string, half the length of the melody string, and even two more, respectively the twelfth and the double octave, not resting on the bridge but acting as sympathetic strings, were sometimes added to improve the timbre by strengthening the pure harmonic tones without increasing the blare due to the action of the bridge.

In Germany, at the time when the tromba marina was extensively used in the churches, nuns often substituted the tromba marina because women were not allowed to play trumpets. In France, the Grande Ecurie du Roi comprised five tromba marina among the band in 1662, when the charge was mentioned for the first time in the accounts. The instrument fell into disuse during the first half of the 18th century, and was only to be seen in the hands of itinerant and street musicians. In modern times, the group Corvus Corax still regularly plays the tromba marina.

The didgeridoo is a wind instrument of the Indigenous Australians of northern Australia. It is sometimes described as a natural wooden trumpet or drone pipe. Musicologists classify it as an aerophone. Some sources state that the didgeridoo had other uses in ancient times.

It is usually cylindrical or conical in shape and can measure anywhere from 3 to 9 feet in length. Generally, the longer the instrument, the lower the pitch or key of the instrument. Keys from D to F are the preferred pitch of traditional Aboriginal players. The didjeridoo functions as an aural kaleidoscope of timbres and the extremely difficult virtuoso techniques developed by expert performers find no parallel elsewhere.

There are no reliable sources stating the didgeridoo’s exact age, though it is commonly claimed to be the world’s oldest wind instrument. Archaeological studies of rock art in Northern Australia suggests that the Aboriginal people of the Kakadu region of the Northern Territory have been using the didgeridoo for about 1500 years, based on the dating of paintings on cave walls and shelters from this period. A rock painting in Ginga Wardelirrhmeng from the freshwater period 1500 years ago shows a didgeridoo player and two songmen. In some Aboriginal cultures, only men are permitted to play it, and women can only use clapsticks.

Authentic Aboriginal didgeridoos are produced in traditional communities in Northern Australia and are usually made from hardwoods, especially the various eucalyptus species that are endemic to the region. Sometimes a native bamboo or pandanus is used. Generally, the main trunk of the tree is harvested, though a substantial branch may be used instead. Aboriginal didgeridoo craftsmen spend considerable time in the challenging search for a tree that has been hollowed out by termites to just the right degree. If the hollow is too big or too small, it will make a poor quality instrument.

When a suitable tree is found and cut down, the segment of trunk or branch that will be made into a didgeridoo is cut out. The bark is taken off, the ends trimmed, and some shaping of the exterior then results in a finished instrument. It may then be painted or left undecorated. A rim of beeswax may be applied to the mouthpiece end. Traditional instruments made by Aboriginal craftsmen in Arnhem Land are sometimes fitted with a wax mouthpiece. This comes from wild bees and is black in appearance with a distinctive aroma.

Didgeridoos are also made from PVC piping. These generally have a 1.5 to 2 inch inside diameter, and have a length corresponding to the desired key. The mouthpiece is often made of the traditional beeswax, or duct tape. An appropriately sized rubber stopper with a hole cut into it is equally acceptable. Some have also found that finely sanding and buffing the end of the pipe creates a sufficient mouthpiece.

The didgeridoo is played with continuously vibrating lips to produce a drone while using a special breathing technique called circular breathing. This requires breathing in through the nose while simultaneously expelling air out of the mouth using the tongue and cheeks. By use of this technique, a skilled player can replenish the air in their lungs, and with practice can sustain a note for as long as desired. Recordings exist of modern didgeridoo players playing continuously for more than 40 minutes. Mark Atkins, in Didgeridoo Concerto plays for over 50 minutes continuously.

A termite bored didgeridoo has an irregular shape that usually increases in diameter towards the lower end. This shape means that its resonances occur at frequencies that are not harmonically spaced in frequency. This contrasts with the harmonic spacing of the resonances in a cylindrical plastic pipe, whose resonant frequencies fall in octaves, fifths and fourths. The second resonance of a didgeridoo, or the note sounded by overblowing, is usually around an 11th higher than the fundamental frequency.

The vibration produced has specific harmonics. It has frequency components falling exactly in the ratios of octaves, fifths and fourths. However, the nonharmonic spacing of the instrument’s resonances means that the harmonics of the fundamental note are not systematically assisted by instrument resonances, as is usually the case for Western wind instruments.

Sufficiently strong resonances of the vocal tract can strongly influence the timbre of the instrument. At some frequencies, depending on the position of the player’s tongue, resonances of the vocal tract inhibit the oscillatory flow of air into the instrument. Bands of frequencies that are not thus inhibited produce variations in the output sound. These variations give the instrument its readily recognizable sound.

Other variations in the didgeridoo’s sound are made with “screeches” related to sounds emitted by Australian animals, such as the dingo or the kookaburra. To produce these sounds the player simply has to cry out in the didgeridoo while continuing to blow air through it. The results range from very high pitched sounds to much lower guttural vibrations.

The didgeridoo is sometimes played as a solo instrument for recreational purposes, though usually it accompanies dancing and singing in ceremonial rituals. For Aboriginal groups of northern Australia, the didgeridoo is an integral part of ceremonial life, as it accompanies singers and dancers in religious rituals. Pair sticks, sometimes called clapsticks or bilma, establish the beat for the songs during ceremonies. The rhythm of the didgeridoo and the beat of the clapsticks are precise, and these patterns have been handed down for many generations. Only men play the didgeridoo and sing during ceremonial occasions, whilst both men and women may dance. The taboo against women playing the instrument is not absolute. Female Aboriginal didgeridoo players did exist, although their playing generally took place in an informal context and was not specifically encouraged. Linda Barwick, an ethnomusicologist, says that women have traditionally not played the didgeridoo in ceremony, but in informal situations there is no prohibition. 

The didgeridoo was also used as a means of communication across far distances. Some of the sound waves from the instrument can be perceived through the ground or heard in an echo. Each player usually has his own base rhythm which enables others to identify the source of the message.

There are sacred and even secret versions of the didgeridoo in Aboriginal communities in parts of Arnhem Land, Northern Territory, and the surrounding areas. These types of instruments have specific names and functions and some of these are played like typical didgeridoos whereas others are not.