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Electronics and Music in Harmony


Lectures at the Institute of Electrical Engineering, P. Conway (Leeds Polytechnic), D. Finlay (City University), K. Jones (City University)


Who would have thought that the invention of the thermionic valve in 1906 would lead to such advanced developments as complex music synthesisers and computers, less than 60 years afterwards. This lecture demonstrated the contribution that electronics has made to music, from early musical devices to one of the latest computer music systems.

Paul Conway, from Leeds Polytechnic, presented a technically biased description of analogue techniques used for sound synthesis. Any musicians present without a mathematical background, would have been bewildered by his quick delve into Fourier analysis and descriptions of early electro-mechanical methods of generating sounds. Fortunately some of the technical descriptions of effects, such as pitch and amplitude modulation, were demonstrated using a Crumar 'Performer' polyphonic synthesiser.

The next lecture was given by Don Finlay from City University, London. Don began by briefly describing how the invention of the digital computer had made possible a new field of music synthesis. However, it is only recently with the cheap processing power of microprocessors, that the individual can experiment. Using a 'look-up table' in the computers memory and a digital to analogue convertor, a Nascom 1 microprocessor was used to give a very close approximation to a sine wave — the basic 'building block' of sounds. More complex waveforms can be synthesised by combining, in different proportions, sine waves which are multiples of the fundamental frequency (this is called additive synthesis). The sound of conventional instruments can be synthesised by changing the harmonic content of a waveform with time. This is the principle used in the new Fairlight CMI reviewed this month. The limitations are the amount of memory available and the speed at which the computer can perform the computations.

Another approach to music synthesis with computers is the control of external hardware, such as a synthesiser: the memory size of Mr Finlay's Nascom 1 was only 4k; consequently he constructed a 9-channel multiplexed system to enable the micro to control 9 v.c. functions of an analogue synthesiser. This was demonstrated using the Nascom 1 to play a melody in 3-part harmony.

The 'piece de resistance' of the evening's lectures was the sophisticated Apple Music System. Kevin Jones, a research fellow at City University, has been working with the Apple to study stochastic composition techniques. Essentially the system consists of special hardware and software which connects to an Apple II microprocessor. Using system subroutines written in BASIC the composer is able to 'construct' his compositions aided by high resolution colour graphics. Kevin had the audience captivated by one of his compositions called 'Turtle Soup', a computer-generated 9-part canon. The combination of the nine parts is randomly chosen by the computer to give an intricate changing collage of sound. To enhance the music the computer graphics are used to display each of the separate parts as it changes pitch. Unfortunately there was not time for the full capabilities of the Apple Music System to be discussed. Nevertheless, the lecture pointed to the microprocessor's increasingly important contribution to the expanding field of electronic music.

As the latest technology makes new music systems and devices commercially available, it becomes increasingly important that lectures such as this can be attended by the general public. Only then will electronic music and the techniques required for its composition, become a medium for contemporary composers as well as home experimenters.



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Music Maker Equipment Scene

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E.M.A.S.


Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.

 

Electronics & Music Maker - Jun 1981

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Feature by Graham Hall

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