of Microprocessors

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tORadModification Methods
All the different methods for generating the sound material necessary for
electronic music can be roughly categorized into two groups: those that
generate entirely new sounds via some kind of synthesis process and those
that merely modify existing sounds. This dichocomy is not very rigid, however,
since many synthesis methods depend heavily on modification of
ot"herwise simple synthetic sounds for their results, and many modification
methods so severely distort the original sound that the result could easily be
considered to be synthetic. Nevertheless, the fundamental component techniques
making up a methodology can be easily segregated into synthesis and
modification processes.
Modification techniques are usually considered to be the older of the
two. Before the appearance of musique concrete, pure synthesis was more
common, but the fundamental goal ofmost of these early efforts was to build
a solo instrument that would fit inco an orchestra. The goal of musique
concrete, on the other hand, was to replace the orchestra and produce works
of the magnitude of a symphony entirely by electronic means.
Modification methods attack sound from every conceivable direction.
Any of the simple sound parameters such as frequency, amplitude, or spectrum
may be directly altered. Time sequencing of the envelopes of these
parameters may be altered in numerous ways. Parameter envelopes charac­
.teristic of one sound may be extracted and applied to another. Even simple
judicious selection of short portions of sounds can give a completely different
effect.
Sound on Tape
As mentioned previously, sound on magnetic tape is a physical object
that may be freely manipulated. The only tools required are a reel-to-reel tape
recorder (two recorders are desirable), a good pair of nonmagnetic scissors, a
splicing block with splicing tape, and imagination. A grease pencil is also
necessary for marking the exact location of sound events on the tape.
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