All musical instruments, including those of the electronic
variety, have evolved from what came before, either in
presentation or in usage.The standard keyboard, for
example, has survived virtually unchanged for centuries!
Percussion
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The earliest forms of instruments involve the striking of one object (possibly the human hand) against another, so creating an impulsive sound. Within this category are drums, shakers and castanets. Most produce an un-tuned sound which consists of white noise (random sound of random frequency) with a hard attack and short decay.
Later percussion instruments are pitched or tuned, as a result of resonance, in which the physical dimensions of the instrument determine the frequency of cyclic oscillation.
The most notable is the drum, made from a skin stretched tightly over a hollow cylinder or hemisphere, which produces both ‘noise’ and ‘tuned’ components. In the horizontal kettle drum (timpani) the tuning is adjusted by tightening or relaxing the skin whilst the bass drum stands upright and is struck on its side.
The modern steel drum is a fully-tuned instrument, as is the xylophone which consists of wooden bars, arranged in a chromatic scale, which are struck using wooden hammers.
The acoustic nature of metal (rather similar to glass, but more durable) provides a high quality of resonance. The sound is pure but rich in harmonics, or upper partials (multiples of the fundamental), which give many instruments their characteristic sound.
The triangle is a suspended rod, folded into a convenient triangular shape, and struck by another rod. Cymbals, either struck with a stick or against each other, are made of concave brass or bronze disks which produce a vast amount of noise. The gong, more popular in eastern music, has a turned rim to give a very resonant note.
The development of metal percussion instruments proceeded along several lines. It was soon found that a rod could be replaced by a tube which could be accurately tuned, so creating tubular bells.
Similar tubes were flared into the familiar church bell, made of an alloy of copper and tin, with more tin than bronze. The shape gives a horn effect which increases the amount of sound projected outwards. A carillon consists of a set of bells in a church tower which is played using a keyboard below.
The glockenspiel is made from a series of bells, metal bars or tubes which are played with hammers. A similar sound is produced by the celesta, a keyboard instrument which uses metal bars.
Strings
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The vibration of any string under tension produces resonance — usually at the fundamental frequency which is determined by the length of the string. It may also vibrate in several other modes so as to produce harmonics. The string can be excited either by plucking, striking, or stroking with a bow.
One of the most ancient of plucked instruments is the harp which uses separately tuned strings for each note, making it relatively easy to play. Modern instruments work on a basic scale of C flat major which is altered by a set of pedals.
The problem with the harp is the number of strings — hence its huge size. In later instruments the player uses fingering (holding down a string at specific points) to adjust the effective length of any string. Many instruments tried to optimise between the number of strings and the complexity of fingering. The ancient Greeks played the lyre, the lute was popular in the 15th and 16th centuries, and the zither, laid on the knees and plucked, is common in central Europe.
The guitar, of Spanish origin, usually has six gut strings covering a range of three octaves. It uses a sound box as an acoustic amplifier. This is carefully ‘tuned’ to cover the entire range of the instrument whilst avoiding unwanted resonances. Alternative fingering can give the same note or chord (a combination of notes) but with subtle variations. The twelve-string version is even more difficult to play! The guitar has evolved further in our own century — to highly tensioned steel strings and electric pick-ups!
The viol, a six-stringed instrument which was played vertically, was popular until the end of the 17th century. Its successors, the treble violin, alto or tenor viola, bass cello, and double-bass, are all played with a gut bow, usually have four strings and employ a sound box. Their sophistication is demonstrated by an amazing ability to express human emotion. Modern instruments are often fitted with ‘acoustic’ electric pick-ups to make themselves heard above the electronic background!
Several attempts were made to create stringed instruments that could be played with ease. One of the first was the clavichord, used in the 17th and 18th centuries, which uses metal tangents to strike the strings. The harpsichord, popular between the 16th and 18th centuries, and sometimes called a cembalo, is basically a harp, rotated by 90 degrees, and plucked by means of quills or leather points controlled by a double keyboard. A smaller version, the spinet, was also available in legless form as a virginal — possibly so named because of its popularity with young ladies of the period!
The dulcimer (cembalo in Italian) places the strings over a sounding-board to increase the volume and hits the stings with hammers, instead of plucking them. This was the prototype for the 18th century pianoforte or piano which uses dampers to stop vibrations when a key is released. Pedals are used to regulate the character of tone (piano = soft, forte = loud). The modern piano, using an iron frame for tuning stability, has 88 keys and is either a horizontal grand or vertical upright.
The piano was soon automated as a player piano, one version of which was called the pianola.
Brass
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Wind instruments operate by causing a column of air or a tube to resonate. Vibrations are initiated by means of the player‘s lips, a vibrating reed or by air passing over an orifice. The earliest wind instrument is the horn (literally made of horn) which resonates and amplifies the sound produced by the player’s lips — the player and the horn together formed the instrument.
More powerful horns employ the resonance of metal. The earliest example is the trumpet, simply a long tube with a mouthpiece at one end and a bell horn at the other. In its most ancient form the note is determined by the player himself. The bugle is a small trumpet used by huntsmen and for military signals.
19th century technology introduced coiled pipes and valves to many brass instruments, including the trumpet. The effective length of this new version is adjusted by three valves to provide a chromatic scale. Another example is the cornet, in which the valves are operated by pistons. In the trombone (known in Early English as the sackbut) the length is made continuously adjustable by tubes sliding one inside another.
The saxhorns, including the saxtuba, are a family of trumpet instruments in which the bell mouth either points upwards or the tube encircles the player’s body. The tuba, the deepest-toned of brass instruments, is fitted with three or four valves.
The saxophone is unusual. Although a brass instrument, it uses a reed similar to a clarinet, and is controlled by keys.
Woodwind
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Early woodwind instruments which use a vibrating tongue or reed include the shawm and hautboy, forerunner of the oboe. The latter is a double-reeded instrument, with a plaintive incisive tone, used in modern form since the 18th century. The bassoon, also double-reeded, is the bass instrument of the oboe family.
The cor anglais (french horn) uses coiled tubes, valves and a wide bell. It sounds similar to the oboe but is lower in pitch. The clarinet is a single-reeded instrument, controlled both by ‘holes’ and keys.
The recorder is a forerunner of the flute — the modern version is blown sideways across a hole and is often made of metal. The piccolo, its smaller brother, plays one octave higher.
Whistle-pipes and penny-whistles are simple tuned pipes with an orifice near the mouthpiece across which air is forced to pass.
Other Reed Instruments
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A wide range of instruments were developed, particularly in the 19th century, which used metal reeds. The simplest is the mouth-organ or harmonica, which uses a separate reed for each note.
The accordion, which later acquired a piano-like keyboard to become the piano-accordion, is driven by hand-operated bellows, in the same way as the early squeeze-box. A later development, particular popular in small churches, was the harmonium, a keyboard instrument whose bellows are driven by pedals operated by the performer.
The Organ
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The organ, really a row of huge whistle-pipes, existed in primitive form in the 14th century. Air is blown through the pipes (at least one for every note) by means of bellows. These bellows, or the person powering them, is called the organ blower. In the 16th century a pedal keyboard was added.
The tone is altered by using different stops which determine which set of pipes is used to play a note. The set controlled by a particular stop is called a register. Such stops could form groups or partial organs (such as great, choir, swell, solo, pedal, organ) each with a separate keyboard. Inevitably such keyboards ended up in a similar form to that of the piano.
Early Electronic Instruments
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 Electric instruments are specialised forms of acoustic
instruments that require electrical amplification to make them
audible — the electric guitar or violin are examples.
Oddly enough, the addition of electronic effects devices has
brought the electric guitar almost into the world of synthesis.
Electronic instruments are different — they use electrical energy to create the original sound. Their sounds do not really exist until they reach the loudspeaker! Synthesisers and electronic organs fall into this category.
Apart from electronic organs there are few examples of early electronic instruments. One example is the theramin, which first appeared in music halls. It used two radio frequencies oscillators, closely tuned to each other, so creating an audible whine. The operator would wave his hands near two metal rods, influencing one of the tuned circuits, which would change its pitch. It was not a phenomenal success — it was eventually used by the Beach Boys in Good Vibrations and also by Led Zeppelin.
The Electronic Organ
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Electronics found its greatest challenge in the traditional organ — the replacement of pipes by smaller electronic counterparts. In the most advanced organs separate oscillators were needed for every note, together with complex keyboard logic to ‘sound’ the appropriate oscillators for each key and stop.
The domestic organ side-stepped all these complications by using a set of simple square wave oscillators for the top octave together with frequency dividers for the lower octaves. The results, particularly at the extremes of the keyboard (where the limitations of output filtering became obvious), were unsatisfactory. A decent instrument could never be produced at a realistic price until the appearance of the microprocessor. But, unlike many synthesisers to come, it was fully polyphonic — you could press all the keys you wanted, and get all the sounds.
 
The Hammond organ succeeded where most others failed. A set of motorised metal ‘tone wheels’, each with precisely machined teeth to give the correct pitch, were positioned adjacent to magnetic pickups which extracted each frequency. The result was a simple and reliable instrument, with a very characteristic sound.
The Radiophonic Workshop created its own unique ‘organ’ consisting of a rack of ordinary test-room oscillators, a small keyboard and a keying unit. As each key was pressed a pentode valve in the keying unit would connect the appropriate oscillator to the output — each valve had adjustable timing for attack and decay. Limited perhaps, but few instruments today would allow you to tune any key to any pitch!
