The development of electric and electronic musical instruments – as well as associated music-production systems – is one of the defining strands in the history of music over the last century. In fact, the advent of electric instruments predates even the twentieth century.

Some of the instruments discussed here – such as the electric guitar – are commonly recognizable. Others, such as the Chapman Stick or the Mellotron, are less well known, while some – such as the ill-fated Telharmonium – are nothing short of bizarre!

Electric and Electronic

The terms ‘electric’ and ‘electronic’ are often interchanged erroneously. By convention, the term ‘electric’ refers to instruments that employ an electrical system to amplify and/or modify a sound that was originally produced by acoustic means. An obvious example of such an instrument is the electric guitar – an instrument in which the sound of the natural vibration of strings is amplified and modified by electrical means.

On the other hand, an instrument like a synthesizer is referred to as ‘electronic’, because it generates its sounds entirely from electronic components – such as oscillators or microchips – with no natural, acoustic origin.

A further subset of electric instruments is those that are known as ‘electromechanical’. This term describes instruments in which an electric motor drives moving parts, which in turn are used to either generate or modify sound. Instruments in this category include the vibraphone and the Hammond organ.

Sound

All sound begins as movement. A drum skin moves upon being struck; a taut string vibrates when plucked; a column of air moves across vocal chords. In turn, such movement displaces adjacent molecules of air. Each molecule then nudges and displaces its neighbour – rather like a succession of billiard balls bouncing into each other, or a ‘Newton’s Cradle’, the familiar desktop toy. In this way, the original movement – or kinetic energy – from the sound source is transferred through air to the listener. This movement of air molecules causes the listener’s eardrum to vibrate in a pattern directly related to the movement of the original sound source – the struck drum or vibrating string. The movement of the eardrum is then translated into electrical nervous energy (interpreted by the brain as sound) via a complicated system of tiny bones and a membrane suspended in the fluid of the inner ear.

Microphone

Put simply, the job of a microphone is to turn sound into electricity. This is achieved by means of a diaphragm to which is attached a coil of wire around a magnet. As anyone who has ridden a bicycle with lamps powered by a dynamo knows, a coil of wire moved in a magnetic field produces an electrical current in the wire. Thus, acoustic energy arriving at the diaphragm of the microphone, causes the coil of wire to vibrate around the magnet. This induces an electrical signal in the wire – a signal that directly represents the characteristics of the original sound.

Loudspeaker

A loudspeaker is, in...

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