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WORK IN PROGRESS

Some unusual examples from the backyards of musical instrument acoustics.

Musicologists have had a hard time reducing the literally millions of musical instruments, tools and objects used by humans for musical purposes, to four, later five, classes of sound making principles. Looking at those, you easily imagine the classical western musical instruments behind them:

Aerophones – flutes, woodwind, brass winds, organs ...
Chordophones – guitar, violin, harp, piano ...
Membranophones – drums
Idiophones – bells, cymbals, vibraphone, xylophone ...
Electrophones – synthesizers

but when you look at the vast output of traditional as well as experimental musical instruments around the world, you soon realize that these categories are not as strictly separated as they might seem. The acoustic, physical reality is much more excitingly complicated and intricate than the theory behind e.g. “just intonation”, whatever that might be. A string also behaves like an air column. A skin resonator can behave like a string in some respects. Percussive elements can intimately interact with strings and air in many instruments. And a tool to excite another object can itself be seen as a part of the instrument – maybe even as the meeting of two instruments in one. Electrically excited loudspeakers are membranes that can be used as tools to excite other objects of different kinds, etc. Let's take a look at a few unusual instruments, formally belonging to the different groups and see that there is nothing normal when it comes to music, it's all an exciting adventure that goes on and on, as long as human imagination and curiosity insists in surviving and reinventing itself.

THE AIR COLUMN/ROOM

The didjeridu, invented by australian aboriginals, seems to be as simple as any wind instrument can be: a ready-made tree branch hollowed-out by termites, just cut off at a convenient length and used directly, sometimes prepared with beeswax for the mouth and wet with water on the inside to make the inner surface smoother. But the “circular breathing” technique provides a constant drone and this single note, sometimes overblown is changed in its quality with the tension of the lips, the air pressure and the voice in order to make intricate sounds, rhythms and imitations of sounds in nature.
	It's easy to construct a didjeridu out of other materials such as a plastic tube. Martin O’Loughlin, living in northern italy, did extensive research on how to expand the tonal possibilities of the instrument and also how to amplify it. His open didg and medusa have a system of tubes and openings connected to a single, amplified mouthpiece. The interesting thing is that the acoustic principles of the instrument differ very much from most western tube wind instruments, in that it doesn't always excite the air column from the end, but sometimes on different parts of it, maybe slightly more related to the ocarina in this respect. Through covering some open holes, he changes the pitch and also in which end the sound projects, but since the mouthpiece is amplified, that won't be a big problem when recording or performing.
	The so called membrane reed is a surprisingly simple way to construct a very effective wind instrument using a balloon or latex material as a replacement of vibrating lips or reeds. It can be constructed in less than a minute, from any tube, a balloon, some adhesive tape and with scissors as the single tool. The air is blown into the balloon and forced over the edge of the tube, and the balloon, applied like a drum skin on top of the tube, vibrates strongly. There have been several different instruments and “organs” constructed from this principle, like the balloon bassoon organ by Daniel Jodocy or psukhô and tu-yo by Jean-François Laporte.
	As a precursor of bag pipes (an anonymous inventor made one out of a condom) and organs, people have since ancient times played many wind instruments at the same time, like the ancient greek aulos or the Sardinian launeddas. The great blind multi-instrumentalist Roland Kirk often played two or three saxophones at the same time. Once he played Sentimental Journey on one and Symphony to the New World on the other! He explained this is possible because one half of the brain says Obladi, while the other says What does it mean?
	Sometimes flutes have been made double from the beginning, e.g. in yugoslavia and South America, or as in Bart Hopkin's Dual Slide Whistle.
	A property of many wind instruments and most flutes is the ability to overblow, i.e. to reach a higher-pitched resonant frequency or harmonic. In some flutes, it is one of the essential features, like the yugoslavian fujara, the persian ney or the scandinavian sälgflöjt (traditionally constructed as a seasonal instrument made when the bark could be separated from a branch in one piece like a tube, but now more often made out of plastic, thus permanent). If you are, like me, not very skilled at flute playing, you can make a ready-made overtone flute out of electrical conduit – the kind that has a corrugated, “accordion” structure that makes it easy to bend. It makes the air tumble and create overtones when you simply blow straight into it, with different velocity. It's related to the whirly, the larger corrugated tube that children often like to swing around and which makes overtones.
	Except by blowing, air containers can be made to resonate from percussive blows on or near their openings. African udu drums are usually made like a ceramic vessel with an extra hole on the side. When you slap the hole with your hand there is one note if you quickly withdraw it and another, an octave lower, if you keep the hand on the hole. The ringing of the ceramic pot itself is part of the sound.
	The vietnamese klong put is supposedly the only acoustic instrument that you play without touching it (if you include electronic instruments, the theremin can also be played without touching). Looking like giant horizontal pan pipes, you clap your cupped hand in front of the opening to excite the air resonance. It's not easy.
	You can use both principles on your own mouth too: slapping your tense, open lips with your hand, or clapping them in front of the mouth.
	Recently I came across the peculiar nepalese/bhutanese yalamber baaja, which seemed to me like a hybrid between a string- percussion- and wind instrument! It's a large bamboo tube with two strings cut out from the length of its own body, still attached in the ends and suspended with small bridges. A wooden piece is clamped between the strings in the middle, above a hole in the tube. Another small hole is cut on the side of the tube and can be covered to change the pitch. It's played by plucking the suspended wooden piece, and the air resonates inside the tube! I've never before seen anything like it.
	A vacuum cleaner can be used as a musical instrument in at least three ways: letting the tube suck the air from the side of your mouth, form your lips into a stiff ring, and you can play a very strong flute sound and change the pitch with changing your mouth cavity. Be careful and clean!
	I've seen a norwegian musician use it backwards, as a blowing machine, with a part of a bicycle tube (that has to be heated a bit by rubbing with the hands in order to make it soft enough) on the end and squeezing it to work as a reed.
	The third way is of course to use the tube as a didjeridu. (Clean it first!)
	The inimitable Sven-Åke Johansson has, with different temporary orchestras, performed the piece MM Schäumend, which is a piece for an orchestra made of different kinds of fire extinguishers!
	The leaflute, or leaf blowing seems to be an Asian tradition where you blow a large leaf folded in a special way. If you're skilled, you can play any melody on that.
	The american Stan Wood plays something he calls vibraband, which, as far as I understand, is a large rubber band that he blows in some way. It's incredible, the melodic expression he manages to get out of something that seems so simple.
	Other seasonal, disposable instruments you can make in a second are grass blowing (stretch a fresh grass between your thumbs, put together on the long sides and blow in the small slit between the knuckles), cinema ticket blowing, and blowing the stem of a dandelion if you cut it slightly in the end to form a double reed which you put inside your mouth.
	Pyrophones are different forms of fire-excited tubular wind instruments in the form of organs or pan pipes. They have a history all the way back to the 1870s by several inventors including Georges Frédéric Eugène Kastner and William Tyndall. The quartz cantabile by Todd Lerew is a small example of many, often huge constructions.
	The singing, ringing tree is a sound installation made with hundreds of bottles on a windy spot that works like a giant pan flute, played by the wind from all directions.
	Sirens are very different wind instruments not used much anymore. As far as I know, they were introduced into the orchestra by Edgard Varèse. The principle is that when a series of slits on the sides of a short drum-like tube pass by similar openings inside another, at the same time as air is pressed through them both from the inside – the inner one starts spinning because of the angled edges in the openings – a tone is created and gets louder and higher in pitch as the speed increases. The incredible volume made them great as warning signals before the time of loudspeakers. They could be operated manually by a handle as well as with an electric motor. But it's also possible to use the same principle in order to make sirens with much softer sound, and also possible to have control over the pitch, like Bart Hopkin's musical siren, where the air from a movable hose is pressed through a constantly revolving disc with a fixed speed and different holes drilled in circles at different intervals.
	Not an unusual acoustic principle, but an unusual way to play it, is the sea organ of Zadar in croatia: A large organ built under the marble steps by the seaside and played by the waves, by architect Nikola Bašić in 2005.
	Unclear if it should be called a wind instrument, string instrument or an idiophone, the bullroarer has been found all over the world from prehistoric times. It is usually a spoon-formed, oval or rhombic piece of wood tied to a string and spun around over the head. In Oceania, it was used in order to frighten away women from ceremonies that are taboo for them. In many areas it is used to frighten away animals in order to protect crop. Now it's often a children's toy. It's possible to make a similar instrument with stretched rubber bands on a box thrown around on a string.
	In the late 70s, Max Eastley, Steve Beresford, the late Paul Burwell and David Toop ‎formed the group Whirled Music, entirely based on instruments that spin or swing around.

THE STRING

There's so much more to a string than simply plucking or bowing! The design of the string in itself is a fascinating topic. The way all its measures (the scaling) influences the sound is vast. The usual ones: material (stiffness vs flexibility, specific gravity), length, width and tension are complicated enough. As a piano technician I have to deal many of those and more in practice.
	One thing that would rid those with “pure intonation” aspirations of illusions is the phenomenon of inharmonicity. It means that, especially in quite rigid strings, such as those of a modern piano, which are made of steel, they have the possibility of high specific gravity combined with high tension, which means more effect and louder sound, however then the series of partials deviate more from the theoretically exact harmonic series, and more so the lower the tension is. That's why extremely out of tune pianos have a low, soft and bell-like sound, which is quite nice actually but won't do if you want to play chords that sound like chords.
	So slack strings are interesting both plucked, bowed and beaten.
	Self-vibrating or false strings are a common problem in pianos and might occur if the strings are dirty, rusty or bent. Of course, this is possible to achieve deliberately, or with preparations such as with clamps etc. Examples are John Cage's prepared piano (screws, rubber etc between the strings) from the 40s, the shruti stick by Ganesh Anandan, and the curious trillium instruments by Bart Hopkin, where interconnected strings change each others timbre!
	The idea of the prepared piano orginated with Henry Cowell already 1914. But since John Cage, its popularity has increased with composers like Conlon Nancarrow, Kaija Saariaho etc and improvisors like Cecil Taylor, Chris Burn, Andrea Neumann (who even commissioned the construction of her Innenklavier, a simplifed, lighter and transportble piano frame), Magda Mayas and Lisa Ullén.
	John Cage didn't really invent the prepared keyboard in the sense of altering the sounds of the strings in different ways. Although not many of them remain, earlier keyboard instruments like the harpsichord had a wide variety of changing the tones with different kinds of stops built into the action. There could be a number of rows of jacks (the plucking mechanism) to choose from, placed on different distances from the nut (the closer, the more nasal) or consisting of different materials (quill, plastic, soft or hard leather); there were different kinds of pads made of leather, paper, string or cloth that could be pressed against the strings to dampen them or make them buzz; different combinations of strings with different tunings; and a swell that opens a lid to give more volume. Some even had extra percussion effects so it would begin to look like a one-man band. In the modern grand piano, there remains only the unacorda (left pedal) that slides the whole action sideways to make the hammers hit fewer strings; in the upright piano there is the soft (left) pedal that changes the distance of the hammers to the strings and sometimes the moderator, which is a felt strip that slides between the hammers and strings. A similar arrangement, but with metal pieces, is the more unusual adaption to make a honky-tonk piano sound. A popular but, if you ask a piano technician, forbidden method is to press a metal thumbtack into the hammers. Another honky-tonk way is to just detune the strings slightly.
	A group that specializes on one alternative playing technique of the piano is The bowed piano ensemble. Since you can't play the piano strings with a bow, except maybe one or two strings, the strings are played with loose loops of horsehair, fishing line or plastic bands. It's a complicated collective activity of as many as the edges of a grand can fit (about 10 people).
	Strings are also great to use as resonances for other sound sources, or for other strings. The sitār, sāraṅgī and many other indian instruments introduced sympathetic strings at about the same time (17th century) as e.g. the viola d'amore of southern europe and the norwegian hardanger fiddle. The historical origin is not entirely known. The high end of a piano, or the “back strings” (behind the bridge) of the treble in grands and many historical keyboards like the clavichord, are undamped and thus work as sympathetic strings, and the common 19th century upright model of piano damping (overdampers) was deliberately inefficient as to give a “romantic” feeling. Special sympathetic strings have also been added to the highest octaves of some Blüthner grand pianos, tuned to the octave or unison.
	European modern string instruments usually have a distinct edge to both ends of the sounding portion of the string, but in many indian instruments you have a carefully crafted, slowly sloping bridge called the javārī (the name also refers to the “jewel-like” sound), that makes the string beat against its surface after it's plucked, thus creating the characteristic sound of e.g. the sitār, different versions of the vīṇā or the tambūrā. They are sometimes carefully adjusted to achieve the desired sound by sliding cotton threads called jīvā under the string to lift it very slightly.
	The materials possible to use for strings are endless: rubber, rope, gut, horsehair (such as many rababs), brass, iron and steel of different qualities etc. Bass strings are often wound with thin and soft metal wire to give more weight while preserving a strong and clear tone in practical lengths. Sometimes the string is just a bundle of horsehair, and Bart Hopkin used twisted string in his twist harp (tuning is done by twisting more or less). Personally I'm fond of disposable materials such as rubber bands.
	A string is not only the part between nut and bridge, sometimes it's divided into many playing portions such as in the cimbalom or koto. The bridge is kept in place by the string tension and can be moved. Hans Reichel has created a pick-behind-the-bridge guitar which manipulates the placement of the bridge, or uses double bridges. If you play the string on one side of the bridge, the part behind resonates in a different frequency so that every note will have a different kind of sound. He made the guitar with combining two necks and dropping the body. This has also been explored by Fred Frith, Glenn Branca in his harmonic guitars (guitars with two bodies sharing one neck), Yuri Landman and by Bart Hopkin in his harmonic zither.
	You can also manipulate the string while playing it, such as lightly touching node points to dampen certain partials in order to enhance others, i.e. to play flageolets. Certain instruments are specially created for this purpose, such as the tromba marina. The tromba marina is an old one-string instrument that in its later versions had lots of internal or external sympathetic strings. But the most interesting feature is its bridge. It's deliberately unstable so that one leg is loosely resting on the surface, vibrating along with the string, thus beating the soundboard and giving it a harsh sound, remotely similar to a wind instrument, which gave it the first part of its name. (The reason for “Marina” is still unclear.) The adjustment of the bridge is very difficult and often it was equipped with a special action to facilitate it, called guidon, that pulled the lower end of the string sideways and had a smaller tuning peg for its adjustment.
	One of my favorite one-string instruments has neither bridge, nor fret- or fingerboard. It's the vietnamese đàn bầu or đàn độc huyền (meaning simply “monochord”). You play harmonics here, too, but make the flageolets with the edge of the same hand that you pluck it with, a difficult technique. The other notes you get through bending a flexible stem with your left hand to the left or right.
	If you play a string along its length instead of across it, you excite its longitudinal vibrations, as opposed to its transversal. These pitches are usually much higher and less dependent on tension than on length. This phenomenon can be heard in pianos too, and recent research has shown that pianos in which you have calculated its longitudinal and transversal vibrations to be in tune with each other, sound more pure than others.
	But those who specialize in longitudinal vibrations need very long strings, and these long-string instruments sometimes fill large halls into installations which make the whole building become an instrument, sometimes with hanging buckets etc. as resonators. Prominent names in this art are Ellen Fullman (since 1981), and Paul Panhuysen (since 1982). The incredible Jon Rose, who has made lots of fascinating relative violin constructions, along with the invented Rosenberg clan and its legends (they even have a real museum!), also made his own versions of the long-string instrument in his fences project, including barbed wire as string material!
	To say a few words about some of Jon Rose's relative violins: his 10-string double violin is, like Branca's harmonic guitars, two bodies sharing one neck, but instead of a third bridge, he uses the finger board to create two sounding string sections with inverted lengths, using a double bow to play them both at the same time. He also made a aeolian doubleneck violin (one neck in each direction sharing the same strings) with a sail that collects the wind to sound the strings. The double-piston triple-neck wheeling violin has mechanized bows, connected to the wheel with pistons, playing the instrument when it is pushed forward or backward. And so many more hilarious things.
	The string can be a longitudinal conductor of sounds, which hasn't been explored very much other than in children's telephones, simply made of plastic cups connected by a stretched thread. Another children's play, usually used for a prank, is the Hartsfiol (“rosin fiddle”), a string of thread or fishing wire you can attach to a window with a nail or suction cup. When it's stretched many meters away to an invisible place, you rub the string with a piece of rosin, irritate the people indoors and run away from a safe distance.
	The late inventor/composer/musician/musicologist Hugh Davies specialized on minimal instruments and objects amplified with contact microphones or magnetic pickups, he played, wrote about and composed for stringed household utensils such as egg slicers, cheese slicers, tomato cutters. Another theme of many of his instruments was metal springs: a bit similar to strings but with different acoustic properties. Also only slightly influenced by tension, more effectively played along their length than across, and inviting for other playing techniques.
	Leaving strings, technically speaking, there is the interesting grey area where the materials for strings can be used in other ways: as open-ended rods if they are stiff enough, or as sticks, plectra or other playing tools if free in both ends. But we'll come back to both options soon.

THE SKIN

So for our purpose, let's forget for a while about the obvious: drums; and look at the skin as a resonator for other sound sources. It is very effective.
	The most common western example of a stretched skin as a resonator for strings is the banjo, with african origins.
	Returning to india, specifically Bengal in the north, and bangladesh, there is a group of one-string instruments usually accompanying the singing of bauls (a religious sect that has been very influential by their practice as wandering troubadours) and others, called gōpīyantrā, gopichand, ektārā, gubgubī, ānandalaharī, oop-gopi or khamak. Some of them have a flexible neck that lowers the pitch of the string when you squeeze it, some of them have no neck but a brass handle to change the tension of the string manually. The string is traditionally plucked (but bowing it can be very nice too) and with the string stretched at a right angle to the drum skin, the pitch becomes one octave higher than if fixed to a more solid spot.
	I haven't found any reference to an indian influence on Luigi Russolo (although he was influenced by eastern philosophy, at least later in life), but the creator of the futurist intonarumori (“noise intoners”) uses the very same principle of a string stretched from the middle of a drum skin in most of his instruments. The string is usually played in a similar way as the hurdy-gurdy: by a wheel operated by a handle or a motor, and the tension of the string or the placement of the bridge, is changed with a lever on top of the box.
	There are, however, european instruments with a similar principle of a sound excited from something attached to the center of a drum skin already from the middle ages: the rommel-pot has a stick sticking out from the skin and is rubbed with a wet cloth or wet hands. The sound is considered very comical, which can be seen in a wonderful painting by Frans Hals where the player is surrounded by laughing and excited children.
	The brazilian cuica, used in samba, is the same thing but the stick is usually inside the drum instead of on top of it. The sound is surprisingly close to the human voice.
	Several drummers, especially in improvised music, have started using drums placed with the skin horizontally, as resonators for all kinds of loose objects that sound less on their own. Already conventional tools used on drums such as sticks and brushes can be used in a wide variety of different kinds of beating, twisting, squeezing and rubbing techniques in order to create less common sounds. When you place a stick on the skin and then rub it with a wet hand you get a similar effect as the rommel-pot, or when you rub or beat it with e.g. another stick, the stick becomes more of the sound source, or movable bridge, than merely beating the skin. The same thing with crushing the brush against the skin with a twisting motion. The difference between the membranophone and the idiophone becomes blurred in the curious feast of materials and frictions. Middle-sized cymbals can get a wah-wah effect if you put them with the center to the skin and press them down with varying force while beating it. Examples of this kind of drummers are many: Paul Lovens, Sven-Åke Johansson (who made a piece for drums and cucumbers, and often uses a pea pistol to play the drums with), Raymond Strid, Ingar Zach, Tatsuya Nakatani etc. Some, like Roger Turner, Lê Quan Ninh, Gino Robair and Jacob Felix Heule, have focused on this way of playing so much that they have reduced the drum set to basically just one drum and a variety of objects, that except for other instruments such as a guitar (Strid) can include large pine cones (Ninh) and metal chains and objects.
	The skin can be a resonator for wind instruments too: the khloy (cambodia) is a bamboo flute that sometimes has a rice paper or bamboo skin as a resonating membrane applied over a hole that is not meant for covering with the finger, and gives a crisp sound. A Chinese equivalent is the di, dizi or d'Tzu.
	They are similar in principle to the kazoo, which is not blown but hummed so it gives a buzzing resonance to the voice. The kazoo is in a giant form called a bazooka (it might be the only instrument that actually gave name to a weapon, if you don't count the Stalin's organ, the german nickname for the Katyusha rocket launcher) and as a voice-changer it's a form of Mirliton. Other examples of that are singing in a comb covered with paper, or in a leaf, used by African shamans to invoke the voice of a spirit. In Africa membranes, like applied rattling percussive elements, change the sound of many instruments such as harps and the gourds of balafons. Membranes have been applied to different wind instruments of all kinds also in Europe, e.g. one of the saxophone patents described one, but seems never to have been successful.

IDIOPHONES

An idiophone is an object that makes sound with its own body, such as typically bells, cymbals, xylophone, wood blocks, vibraphone, glockenspiel, celeste, the singing saw. What is not, at least potentially, an idiophone? Also strings and skins can be considered idiophones used in non-traditional ways. Only aerophones and electrophones escape this, since it's hard to consider air and electrones as “bodies”.
	So here, the whole spectrum of everyday objects and materials opens, such as paper, plastic, tools and ready-made objects. Machines have been used by many, such as the aeroplane propeller in George Antheil's Ballet mécanique. Sven-Åke Johansson and Olle Hemmingsson have made compositions for or played with tractors. Other kinds of machines or machine parts have been in use by the group The Sons of God – who also have the piece Drive Chairs where they pull and push chairs around. Rolf Wallin composed a piece for a big balloon, and Judy Dunaway has specialized in different ways of balloon playing with a great variety of expression. The multi-media group Nya kulturkvartetten included many invented instruments, among them a weather ballon with croquet mallets.
	Anna Homler and Martin Klapper are among those specializing in toys.
	Tuned percussion can also be made of stone, thus called lithophones. They seem to have existed since prehistoric times and all over the world, especially eastern Asia. Pinuccio Sciola's pietre sonore or “sound stones” are large rocks that he made regular cuts in in lines and squares, played by rubbing them with his bare hands and by other means. They produce a wonderful whistling sound. The great stalacpipe organ in Virginia’s Luray Caverns, created by Leland W. Sprinkle, plays selected stalactites with different notes with mecanical hammers, arguably the biggest musical instrument (at least to the area).
	The Vegetable Orchestra, based in Vienna, makes and plays flutes and percussion out of .. vegetables.
	Especially under poor conditions, idiophone percussion has been made out of found objects or available resources with great effect. Bamboo stamping tube ensembles, tamboo bamboo, was a way of making carnival music in trinidad when the british forbid the use of drums. The pans or steel drums were then developed from thrown away metal buckets and oil containers.
	The cajón, with afro-peruvian origins, is simply any wooden box, a similar poor man's drum that spread to cuba and to spanish flamenco, blues and folk music everywhere and developed with additions such as snares. Nya kulturkvartetten played a large cardboard box as a bass drum.
	Maybe even the human body can be considered an idiophone (and an aerophone when you whistle, and a chordophone when you sing?), some percussionists specializing in sounds derived from the body alone, such as the nigerian artist Joseph Omotoye, aka Jojo Bodybeats. He calls his act or instrument the Bodiophone. The clapping and stomping of many dances around the world such as flamenco and tap, where the meeting of the feet/shoes and floor surface (sometimes they bring their own floor) creates the music, can be seen as an instrument, in some cases in combination with foot jingles such as in indian dances, hand-held instruments or song.
	One family of idiophones are scrapers, that can make a roll, a noise or a recognizable tone. Somewhat between all of those effects are the sounds of frog calls, that usually look like a frog, with a line of notches on its spine. When you scrape it, the resemblance with a real frog call is remarkabe. Bart Hopkin's scraper flutes use the same function in a set of tuned tubes with ridges to scrape, or a tube with tone holes just like an ordinary flute. Hopkin's Savart’s Wheel uses the friction of ridges around a rotating wheel against which he scrapes special plectra with cones to amplify the sound. The ridges are calculated to give different notes so you can play a melody.
	The same principle counts for the rumble strips and bott's dots that are meant to make sound to make drivers alert in dangerous places or near edges or crossings. The asphaltophone by danish artists Steen Krarup Jensen and Jakob Freud-Magnus is the first adaption of a melody to a road. The melody road by japanese Shizuo Shinoda, the singing road in south korea and the civic musical road in California are other versions.
	Bird calls use a wide variety of sound-making principles, e.g. the twisting of a rosined brass cone in the hole of a piece of hardwood makes a beautiful and strong chirping.

ELECTROPHONES

Except synthesizers, let's look at other electric sound makers that have been used as musical instruments. Maybe the radio is the first one. John Cage composed several pieces including radios, which fit well with his concept of indeterminacy (systems of including elements of chance and unpredictability into his compositions). The guitar improvisor Keith Rowe has also used the radio with a similar idea. Birgit Ulher in Hamburg has a radio speaker in one of the mutes for her trumpet, thus being able to modify the sounds from the speaker as well as that from the trumpet by manipulating the positions in front of the bell. In her duo with Gregory Büttner, the sounds come from his computer.
	The intercom has been used by myself sometimes to distort the voice and make feedback and other weird signals. The microphone can almost be seen as an instrument in itself the way it can be manipulated in order to make feedback or distort other sounds. The tape recorder and gramophone have been used very much to reproduce samples of sound into live situations where that sound is hard to find in a natural way, such as in Ottorino Respighi's Pini di Roma from 1924, where a nightingale has to sing in a certain place, one of the first orchestra pieces to include recorded sound (resulting in a booing audience, at least then).
	Now so many have been using recorded sound that it's hard to know where to start. But maybe more interesting here is when the special features of the recording devices have been manipulated to make more than just a reproduction of recorded sound. The gramophone, often combined with a dj mixing desk, have been used to extreme virtuosity by scratching artists in many different musical genres, sometimes altering the gramophone constructions with multiple tone arms, or reconstructing the records by gluing many together, displacing the center hole etc, and playing both records and gramophones in many unintended ways. Christian Marclay, Otomo Yoshihide, the Berlin-based duo Vinyl Terror and -Horror and Ignaz Schick are some of the improvisors that should be mentioned here among many.
	To play cassettes, sometimes manipulated in different ways, has been used to become a major instrument for some musicians like Aki Onda, Andrea Ermke (also minidiscs) and Pär Thörn.
	Feedback in different ways has been the subject of a range of musicians and composers like e.g. Merzbow (Masami Akita). When the signal from a microphone is amplified back into the mike, you get feedback that is usually painful and dangerous to the ears. If you control it carefully, though, it can be used musically, e.g. using electronic effects or acoustic manipulations of the resonating environment. I have myself used feedback with contact microphones attached to resonating objects and manipulated them through a mixer equalizer, holding my hands in different positions between the speaker and the objects, and by touching certain resonating points on the objects, thus influencing and changing the resonating frequencies.
	Steve Reich made the piece Pendulum Music 1968, where three microphones swing back and forth in long chords over a speaker each. As the swing declines, the quick feedback bursts on every passage, become longer until they are eternally sustained. Some create electronic instruments based on amplification loops of electric signals, without going through microphones and speakers. Some, like Toshimaru Nakamura, feed back signals through a mixer that has no other input, the feedback starts from the inherent noise and then quickly rises to playable tones and beats that are hard to control.
	A merge between an electronic and a string instrument is Alvin Lucier's Music on a Long Thin Wire 1979, using a sine wave oscillator to drive an up to 24 m long piano wire, leaving it for any influence for up to several days. Lawrence Casserley has also projected sound into strings using piezoelectric tweeters, and the principle behind my realization of the singing coffin is inspired by him.
	P.W. Schreck used the fact that recordings, before the age of magnetic tape, and except for acetate discs, were recorded on wire. He combined their use as recorded material and as string in his piano harp constructions. This all happened by chance. His uncle found a burnt-down piano, which he stripped of the wodden parts in order to save the frame for selling as scrap metal. When P.W. worked as a garbage man, he found an old wire recorder and rolls of wire recording (all containing anti-communist ramblings) and got the idea to string the piano frame with that wire, and play it dragging the playback head against the strings while playing them, which produced a mix of feedback and recorded sounds mixed with the string sounds. Eventually, he recorded his own playing with the wire recorder and then strung the string back with the recorded wire. (Everyone thought P.W. stood for Piano Wire, but it's actually the initials of his first names.) P.W. Schreck seems to have sadly disappeared from any archived media, partly because of his bad luck and his disdain for academics and established taste, and so is waiting for a revival.
	Another way in which Alvin Lucier used electronic signals to drive acoustic sounds was his 1965 composition Music for Solo Performer, in which his amplified brain waves are sent to loudspeakers that vibrate percussion instruments spread out in the concert hall.
	The loudspeaker as a driver of loose acoustic objects has been developed by e.g. Jacob Riis (speakers prepared with aluminum foil), Gregory Büttner (speakers driving eating sticks and food containers), Lionel Marchetti (table tennis balls) and Pär Thörn (coins etc).
	The swedish Daniel Rozenhall and Mats Lundell used signals from face muscle nerves to make sound as well as a visual projection in the performance piece I.
	The live electronics genre of filling a table with electronic gadgets might have been started by David Tudor and has hundreds of followers. Except for that and many other interesting things he did, his musical installation Rainforest was again projecting electronic sound into different resonating metal objects. I was involved with a project with a similar idea, Mubil, the Electro-acoustic Van, where Luc Kerléo built the sound system to transform our van into a combined stage and instrument.
	Circuit Bending, a term coined by Reed Ghazala, uses cheap salvaged electronic gadgets that make sound (like toys and old Casio synthesizers) and have an accessible circuit board that you play with your fingers making intuitive or random short-circuits, or with connectors on certain soldering points, sometimes adding potentiometers etc. Some circuit-benders pride themselves with playing intuitively, without knowing much about what they actually do – Hardware Hacking though, a term, as far as I know, from Nicolas Collins, who wrote a splendid book including the term in the title, are trends to make “hand-made electronic music” with a little bit of knowledge, and is an open field of exploration and experiments with all things electronic.
	Voice Crack, a long-running but now defunct duo that consisted of Norbert Möslang and Andy Guhl, was an example of the latter. Their work was at first multi-instrumental and eclectic (using long string instruments among much else), and developed into a purely electronic setup that largely consisted of sound derived from electronically “sniffing”, with elecronic coils, the electromagnetic emissions from all kinds of electronic objects that they spread out on a large table.
	Dr Zeus aka Terry Blake, plays the zeusaphone and gigantor etc that make sound, and great lightning visuals, with Tesla coils.

TOOLS

In practical terms, if we go back to acoustic reality, sound is emitted from objects when you make them vibrate in audible frequencies. There are many ways to ignite such a vibration, as we have seen: with an air stream, with parts of your body, with magnetic oscillations and with tools that excite a momentary pulse or continuous friction in contact with something else. The myriad of the kinds of friction that are possible is exciting. Let's look at some tools that are much more useful than you might first think.

The stick

I've noticed that the first impulse of many children and adults that are newcomers to the world of acoustics is to beat. Take something and beat it against something else. Even before speaking, children explore the excitement of repeatedly dropping or throwing an object. It's an experience of communicating with the objects around you as well as with the people around you, enough for calling it the beginnings of a musical experience. But to continue beyond the beating is rare and demands more imagination and sensitivity to materials and a certain skill with the hands.
	A stick can be scraped, leaning slightly backwards in its direction compared to a right angle against the surface. Almost any kind of stick, of any material can induce a tone, squeak, scraping sound or even a jumping beat if you manipulate the pressure, angle, distance of the hand from the end of the stick and the rigidity of the grip. It is possible to play on these parameters alone to make interesting music. The stick can be of wood, metal, plastic, rubber; be manufactured or from nature, be a piece of string or electric cable, be thin, thick, hollow, have coarse or fine surface, or not even be a stick, it could be plastic cutlery, dolls, credit cards, playing cards, records, paper or even your finger, there are no strict borders.
	The surface can be a table, floor, wall or window, laquered and smooth or worn out; stone, ground or natural; sand paper, paper table cloth, fabric, glass, tiles, cardboard, floors; wet, dusty or dry etc.
	In school, I think most of us have played a ruler that sticks out from the edge of the desk, holding it firmly at a distance of a few centimeters from the edge to explore the variety of sounds and pitches achieved when you manipulate the parameters. Any stick that is a bit rigid and a bit flexible can be used in this way, like a knife or a plastic cocktail stirrer. One of my favorites is the springy flat metal rods that fall off street sweeping machines as they do their work and are thus found almost on any street in any city, especially with cobblestones or other uneven surfaces where they easily get stuck and break off.

The bow

can be seen as a stick too, or as a monochord: it can be played by another bow (I got the idea from Jon Rose, who sometimes did only that – he developed different versions of a bow at STEIM in Amsterdam with a sensor that transformed the pressure into midi values which were fed into a synthesizer or software for visuals and quadraphonics). It can play strings in a lot of exciting, unusual or “wrong” ways by playing the string on different places (known for violin players as sulla tastiera, sul ponticello), “crush” to use more force and less speed to make more coarse noises. Experimental string players can often be seen playing directly on the bridge or the string holder. The bow is useful for so many more materials than just strings. My first bowed instrument is the saw (inspired by Hal Rammel) and so almost anything that has a thin enough edge that is not too rigid or too flexible, can be played: thin wooden, metal, plastic or cardboard boxes (which has been explored by Sven-Åke Johansson) or sheets, the ruler at the desk, the playing card, any paper.
	The story goes that a german violin player was going to hang his bow on a nail sticking out from the wall and slipped so he played the nail and was excited by its clear and strong tone. Then he invented the nagelgeige or nail violin, which can be seen in many different appearances in musical instrument museums but unfortunately is rarely heard.
	A whole range of instruments have been developed from this principle, though, of which the most famous is the waterphone by Richard Waters and played by Spock in Star Trek! A metal bowl with standing metal rods coming out from the rim, it actually contains a small portion of water that changes the resonance of the sounds coming out from bowing, beating or rubbing the rods and the bowl.
	A similar principle is employed in Hal Rammel's triolins (metal rods on a triangular wooden sound box) and amplified palettes (wooden and metal rods, saw blades etc mounted on a painter's palette). And, inspired from Hal, I made similar constructions in the hedgehog, whalefish and metal harp. In the latter, instead of rods, there are metal blades around a tube, mostly played with a bow.
	The Baschet brothers created many instruments of which the cristal baschet might be the most famous one. The sounding parts are metal rods, amplified with metal sheets, but excited in a peculiar way: attached at a right angle to the rods are glass rods that you rub with wet fingers.
	A similar way of sending vibrations to something else on a right angle, is Bart Hopkin's stroked zither – but instead of stroking a rod to excite another rod, you stroke a string to excite another string.
	Also using metal sheets as amplification, but of strings, is Bob Rutman's Steel Cello. A further developed version with rods by Jan Heinke is played by the ensemble Stahlquartett.
	There is a peculiar keyboard instrument that is also only preserved in museums and never heard playing, although it even has two names: the terpodion or uranion, and a later version called melodion. I showed interest in hearing it to the director of the museum in Leipzig, which has one, and the museum also at the time adapted the idea to keep the instruments in playable state, but he was very reluctant and just said it sounded schrecklich! Only 43 poor seconds can be seen on the internet. The principle is simple: wooden and metal rods are pressed, through the keyboard action, towards a rotating cylinder.
	Bowed keyboards is another subject which mostly belongs to the string section, but whith the wheel seen as a version of the bow, it can belong here too. It should be mentioned that Leonardo da Vinci's old invention (never realized, like so many of his ideas) has been developed in modern time into the wheelharp. Similar to the hurdy-gurdy, but instead of playing single strings with keys, it's fully polyphonic as to make it possible to play chords since each key has a string that can be pressed to the wheel through a keyboard.
	What is a bow? Although technically it would be horsehair stretched in tension on a stick with some distance, the functions of a bow can be performed by other objects, too, like a stick with a resistant surface fit to the purpose of achieving a repeated stick-and-slip motion of its subject, be it a string or an edge of something. A more coarse stick-and-slip motion is achieved if the stick is notched. The devil's fiddle, relative to the stumpf fiddle, bumbass or brumbass often uses a notched stick that almost looks like a saw to play the single string which has an action with a beater that beats against a drum, making then a drum roll sound. These instruments are one-man bands with medieval origin and often elaborated beautifully with a devil's head or other comic embellishments.

Plectra

When I made a contact mike-amplified combination instrument called the Whalefish, I soon discovered that the range of tools used on it consisted the major part of the sounds made on it. My friend and colleague Sören Runolf (who plays the guitar among other things) once called them my “plectra”. This made me realize even more the floating border between tools and instrument, and that they often can't be properly distinguished from each other, since the friction made between them is truly a meeting between two equal materials. Like so many other contact mike-based musicians, I use a variety of sound makers, like tools, kitchen utensils, toys, sticks etc. Some of my many colleagues more or less in this vein are Adam Bohman (London), Martin Klapper (Prague/Copenhagen), Eric Leonardson (Chicago), William Davison (Toronto), Tore Bøe (Las Palmas) and Tom Nunn (San Francisco). The latter has specialized on using combs, often cut in different shapes, as tools with great virtuosity and variety on his cardboard-based, contact-miked Skatchboxes, which also integrate combs, and other beautiful instrument constructions. Also Bart Hopkin made a comb instrument where the combs are tuned to a scale. Here, the combs are mounted on a box and played with plectra.

RESONANCE

Resonance is, in one way or another, fundamental in most acoustic instruments. It is the basis of the standing wave, which happens when an ignited system is searching for the minimum loss of energy, and it happens to be a regular vibration. That counts for most strings, winds and tuned percussion. In order to transfer the most of the energy into the air (making an audible sound), instruments are usually designed for maximum volume. In winds, that might be a bell in the end of the air column, in strings, it is usually a wooden board designed to have maximum flexibility, within the limits of stability of the instrument, in the middle, close to the bridge, and maximum reflection along the rims, to keep the soundboard swinging.
	As we have already seen, strings can also be resonators, then often in chosen pitches, and a cavity can also have a resonator effect (though often exaggerated) in e.g. guitars and violins, the tubes under a vibraphone or the gourds under a balaphon.
	We have also already seen that the drum skin is a great resonator.
	To complete the picture, also idiophones can be resonators, like the bent metal sheets in Baschet instruments, or the metal springs in a classic spring reverb.
	And to speculate a bit, magnetic induction, such as used by Voice Crack, could potentially be seen as a form of electric resonance.
	The reverse way of a magnetic pickup, which receives energy from metal strings, are the popular e-bows, who reinforce the string's own resonance and increase its amplitude, thus the name since the increased volume reminds a bit of bowing.

The mouth cavity

Let's look at an unusual, but very ancient and effective, variable air resonator: the mouth. In David Reck's Music of the Whole Earth, there is a picture of a man from new guinea with a captured sago beetle on a straw, held in front of the mouth. The futile fight of the beetle's wings makes a drone that the man uses to enhance certain partials of in his mouth, just like a jew's harp. To modify the spectra of a sound close to the mouth is an ancient idea that is probably as old as talking, and exists all over the world, like jew's harps do. They can be found made of steel (scandinavia), brass (southeast asia), bamboo (philippines), palmwood, ivory or bone, with one or many (southeast asia) sounding tongues or lamella passing through a narrow slit that is part of a frame. Played with pulling a string (nepal, indonesia) or plucking a protruding part of the tongue (europe) or tapping or plucking the end of the frame (southeast asia). Held against the lips (southeast asia) or the teeth (europe). Here we have an example of an instrument that has been hard to classify because of the meeting between two media: idiophone or aerophone?
 	I've discovered you can use the squeek of the air coming out of a balloon when you pull the sides of the hole apart, in a similar way in front of the mouth. I've seen Han Bennink do it with a bell, and I've tried it on the saw.
	As a child I learned how to knock a wooden ruler held against the cheek and make different tones with the mouth. The clackamore uses the same principle as a melodic percussion instrument but with a mechanism. The mouth bow, with african origin, has the same principle for a string instrument, developed in different ways by Colin Offord. He uses the same amplification idea as the Stroh string instruments, an old gramophone pickup connected to the bridge and a horn – but in his case to a tube into his mouth.
	The mouth can very well be used for amplified sounds using the talk box. The principle was originally invented 1939 by amateur radio operator Alvino Rey, who used a military throat microphone in reverse to send his electric steel guitar sound into the throat of his wife, hidden behind a curtain. It was soon marketed as the sonovox. Later versions have an external loudspeaker in a box which projects the sound into a tube that you put in your mouth. The sound is then amplified with a singing microphone. Peter Frampton is one of the most famous musicians, most of them electric guitar players, that have used it.
	Of course, you can use the same principle with any other flexible air resonator, like Bart Hopkin's formant changer, or the classic leslie with rotating speaker and reflector, an invention from the 40s but known mostly from Hammond organs.
	The nose flute could be in the aerophone section, but its way of blowing a flute note from the nose into the mouth, which changes the pitch, uses the same principle as above. A very portable and convenient instrument that has been made of metal, plastic – and celery by japanese vegetable instrument player heita3 (his youtube name)!

The wooden resonator

But let's look at some peculiarities with the wooden soundboard. Like piano tuning, to make a good work, it's an art of compromise. A thin board will be resonant, but too thin will break. A solution is to strengthen with ribs. Pine is resonant, but fat and weak, it will easily be damaged. A light material can easily be set in motion, but a heavy one will stay longer in motion and will have more energy to move the air. Flexible will follow all frequencies, but stiff will reflect better. Edges and stiff parts will reflect high frequencies. Middle and flexible parts will reflect low frequencies.
	The violin solution to this is to use well-seasoned spruce, to have thicker wood near the bridge, and thinner near the edges, a difference between about 2-6 mm, except for factory-made violins that are all even.
	The piano solution is basically the same, just bigger, and without an air resonator. In many ways, flexibility within a rigid rim reminds of a drum. However, I was puzzled when I saw an unusual solution on a grand: the sides of the soundboard were open, which seems to be one step towards the string: a sheet of wood suspended between two ends ... that piano reflected the bass very well, maybe because it allowed for larger swings of the soundboard.
	A handy and old resonator has simply been to put an instrument like a zither or a kantele (which in its ancient version is very soft, it doesn't have any bridge) on a table. Then the table suddenly becomes an extra resonator. Think of the noise you make when you stir a cup of coffee. Compare it to the much less noise if you lift the cup from the table! The trick mentioned before with a knife or ruler, sprung against the edge of a table or chair also uses it as a resonator. Much like the mbira, sanza or thumb piano, by the way.
	To complicate the situation slightly, the soundboard of a string instrument shouldn't strictly be called a resonator but rather a radiator of the sound. The reason is that it's not desirable (except among a peculiar sect of violin makers) to have a clear resonance tone in the board. When this happens, it will distort or weaken notes that are slightly close, but not identical, to it. This is known as a wolf and is a problem in many classical instruments. Wood is usually a good material to radiate frequencies rather evenly. Metal, however, is more problematic. The makers of the Stahlcello note how different notes are amplified differently by the steel. This can be seen as adding to the character of the instrument rather than as a problem, though.

Tube resonator

Brenda Hutchinson used long tubes to sing in, and explored the resonances that influenced the note of the singing. Especially the wolf notes, where the note of the voice is just slightly away from a natural harmonic in the tube, are interesting. I have tried this myself, and the power of these resonant frequencies is overwhelming. The voice, or whistle, involuntarily jumps out of your control, a weird feeling.

Amplification

With electronic amplification some of those compromises no longer apply. E.g., the body of an electric guitar has given away flexibility and has been made very rigid. (The compromise is then instead with the strength of the guitarist's back!) Thus, the string tones can be suspended in vibration much longer because no energy gets lost in moving a sound board and the vibrations are effectively reflected back into the strings. The magnetic pickup takes some energy too, of course, but much less than the ordinary bridge.
	With the magnetic pickup and the piezoelectric contact microphone, the concepts of resonance and damping are redefined. The microscopic (“microphonic”?) can be favored, and low frequences can be much more amplified. John Cage amplified cacti‚ and in Cartridge Music 1960, pickups for phonograph needles amplify toothpicks, matches, slinkies, piano wires, feathers, etc. Contact mikes are used on chairs, tables, waste baskets, etc. The live electronic improvising group Musica elettronica viva that started in Rome 1966, used contact mikes on, in the words of Alvin Curran, “anything that sounded and amplified [our] raw sounds: bed springs, sheets of glass, tin cans, rubber bands, toy pianos, sex vibrators, and assorted metal junk”.
	Many electric guitar players have explored the possibilities offered by the magnetic pickup of their instrument. Any electromagnetic field close to the pickup induces noise into it like from e.g. electric motors. Keith Rowe does that on his guitar, and Davey Williams has a whole array of object guitar implements from the electric boxing glove to the electric dinosaurs.
	If this is the thing you want to specialize in, you can just rip the pickup out of the guitar and play that alone, like Martin Klapper a.o. Hugh Davies used the pickup from old telephones. But an even easier and slimmer solution would be to just use a simple coil on its own, like the electronic “sniffing” of Voice Crack or Nicolas Collins. Coils can only be used to amplify electromagnetic fields though, so if you want to amplify other vibrations, they must contain, or set in motion, a metal object. To avoid this, the piezoelectrical contact microphone is very cheap and rather easy to build, even with rudimentary soldering skills. Piezo elements are not always easy to find, but if you just want to start with a few, rip open a musical greeting card or any thrown-away toy or electronic gadget that makes a noise. They usually have a small piezo speaker that you can just reverse and use as a mike! On my web site there are more tips about this.

EXPLORE!

The world of musical instrument acoustics can be very simple, very complicated and surprisingly diverse. You have never heard it all. I find it the ideal way to explore and expand your knowledge, skill and sensibility, to use your hands, ears and eyes, your imagination, calculations, crafts, knowledge about all kinds of materials and tools in order to create new and ever expanding worlds of new sensibilities, surprises, expressivity and poetry. It's a place for imagination, science and practical skills to meet. It's play and global communication. It's strategy and adventure. The more you learn, invent and improvise, the more possibilities open for you and the more surprises you can get, just like in life.

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KOLLA: 
Instrument modifications & extended performing techniques (HD)
http://www.oxfordmusiconline.com/subscriber/article/grove/music/47629?q=Hans+Reichel&search=quick&pos=14&_start=1#firsthit
String
http://www.oxfordmusiconline.com/subscriber/article/grove/music/45984?q=string&search=quick&pos=1&_start=1#firsthit
Instruments, classification of.
http://www.oxfordmusiconline.com/subscriber/article/grove/music/13818?q=classification&search=quick&pos=1&_start=1#firsthit
Experimental music.
http://www.oxfordmusiconline.com/subscriber/article/grove/music/A2224296?q=dripping&search=quick&pos=5&_start=1#firsthit
Sound effects. (Hugh D)
http://www.oxfordmusiconline.com/subscriber/article/grove/music/47631?q=Simon+Desorgher&search=quick&pos=1&_start=1#firsthit
Sound sculpture.
http://www.oxfordmusiconline.com/subscriber/article/grove/music/47630?q=Ellen+Fullman&search=quick&pos=1&_start=1#firsthit

Experimental musical instrument
http://en.wikipedia.org/wiki/Experimental_musical_instrument

Percy Grainger?
Cross-Grainger Kangaroo-Pouch Tone-Tool 
	Australian composer Percy Grainger tinkered with developing what he called "free music machines".
	This electronic contraption, completed in 1952, uses paper rolls to operate a set of oscillators, producing what has been described as the sound of "four air-raid sirens going on at different pitches." A far cry from the composer's arrangement of Country Gardens...
http://www.limelightmagazine.com.au/Article/288901,the-12-wackiest-musical-instruments.aspx/6

Paul Lytton

Eugene Chadbourne: electric rake, ballons

Herman Müntzing

Celery nose flute namn?

singer in the tube! BRENDA HUTCHINSON???? 2,90 m lång tub! http://www.sonicportraits.org/bio.htm

John Boyle?

Marta Zapparoli Penelopex also cassettes...

Peter Vogel? (Mekaniska kretsskulpturer som ställdes ut i Bergen)

Zimoun?

Magda Mayas prepared piano + clavinet?
Annette Krebs prep guitar

Bryan Day tape measure instrument?

Kse Diev, kambodian “instrument of the heart”, an ancient one-string stick zither with an open gourd that you play with a plectron stuck on one finger and change resonance harmonics against the chest just like with the berimbau.

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1889 ståltrådsspelare
[‘talking pictures’ in 1928 och början av utvecklingen av optiskt ljud för film]
All direct recording systems for broadcasting were superseded by the use of ‘acetates’ (direct-cut discs where the recording was made into a film of cellulose acetate on a metal or glass disc), widely used by broadcasting stations during the period 1935–55.
[Marinettis grej är från 1935]
1934, BASF rullband av “cellulose acetate base tapes coated with ferric oxide”
late 1960s kassetter
1972 videoband av olika slag
1983 cd
beginning of the 21st century minidisc, DAT, DVD, CD-R, Internet

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VIDEOS [bädda in och dela upp i 7 delar!]

Bibliography
A picture that I scanned from David Reck's Music of the Whole Earth, p 12, Charles Scribners 1977. (The red palm weevil, Rhynchophorus ferrugineus, is a species of snout beetle also known as the Asian palm weevil or sago palm weevil.)