Computers and Music
By Robert A. Moog
[Robert A. Moog is the inventor of the practical music synthesizer and
president of Big Briar, Inc., a Leicester, North Carolina, firm
specializing in the design of custom electronic instruments.]
For some of us, the idea of an electronic muse is scary; after all,
music is an essentially human activity, while electronic equipment,
especially the computer, is "mechanical" and "unnatural." Throughout
history, however, music has been closely linked to technology.
Except for the human voice, the instruments of music-making have
always been "high-tech" in their time.
THE ELECTRONIC MUSE
-------------------
The violin, pipe organ, and trumpet are complex constructions that
were as "unnatural" when they were first developed as the computer is
today. The piano and saxophone, those vital elements of our musical
experience, were triumphs of manufacturing technology a century ago.
Musical instrument designers have always employed the most advanced
technology of their time. Now, in our time, electronic and computer
technologies are preferred for new musical instrument development.
But this is not to say that musicians are embracing electronics just
because it's the "latest thing." As a group, musicians favor
instruments that a) sound good and b) offer musically useful ways of
manipulating sound. Increasingly, musicians are drawn to electronic
instruments -- not because they're easy to play or sound like
traditional acoustic instruments, but because they offer new tone
colors and new ways of making music.
What's more, musicians have been experimenting with electronic
instruments ever since the first vacuum tube was invented
three-quarters of a century ago. Even before that, musicians and
musical instrument builders were collaborating to harness the
forerunners of electronics and computers to the service of the
muse.
For a growing number of musicians, computer technology is the greatest
advance since the invention of catgut. Music is a form of
communication -- of organizing and transmitting data. The "alphabet"
of music consists of notes.
Melodies, chords, and rhythmic patterns are the "words" and "phrases"
of music. Just as computers can generate "characters" to make text
or a graphic design, they can also process a stream of numbers that
represent a sound waveform. And just as word processing programs
endear computers to wordsmiths, today's composers, performers and
music teachers are all exploring the computer's ability to handle
musical information.
If you understand the general principles of computer operation and if
you like to listen to music, you'll have no trouble following the many
ways that digital technology and computers can be used to make music.
Just keep in mind that computer music is a natural extension of
traditional music and uses programs that are only slightly different
from your basic word processor or data handler. As we shall see,
simulating a multitrack recording studio on your monitor screen is
done with software that is directly related to the
program used to "compose" this article.
MUSICAL DIGITS
--------------
All sounds, musical or otherwise, are vibrations of the air, at rates
of roughly 20 to 20,000 times a second. If the vibrations repeat
regularly, the sounds are pitched (like a guitar or clarinet tone).
If a sound vibration does not repeat regularly, then it sounds
pitchless or "noisy" (like a cymbal crash). In a pitched sound,
the rate of repetition is called its frequency; the greater the
frequency, the higher the musical pitch of the tone. The strength of
the vibration is called its amplitude; the greater a sound's
amplitude, the louder it is.
The shape of a vibration is called the waveform. You can think of the
waveform of a sound as the graph of the air pressure at a particular
point over time. The waveform is an abstraction that we use to
describe the sound. It happens to be n abstraction that has a lot to
do with the tone's perceived quality.
A loudspeaker (speaker, for short) is a device that converts
electronic vibrations into sound. In talking about electronic music
and computers, we generally refer to electrical waveforms that exist
inside an instrument's circuitry. When we refer to these waveforms
as if they were sounds, we assume there's a speaker somewhere and that
we're using it to produce the sounds.
A personal computer may contain its own small speaker
(e.g. the Apple ][), may use the speaker of the TV to which it is
connected (e.g. the Atari or Commodore 64) or may require connection
to an external sound system like most high-quality music synthesizers.
Most electronic pianos, organs, and synthesizers use "analog" circuits
that produce smooth waveforms. Digital computer circuits, on the
other hand, work by switching on and off.
How does a computer produce a musical tone? In most computers, you
can turn the speaker on and off as is it were, say, a memory location.
You can produce a tone by writing a simple program to a) turn the
speaker current on, b) wait a very short time, c) turn the speaker
off, d) wait again, and e) repeat the above steps a specified number
of times. The waiting time determines the pitch of the tone, while
the number of cycles determines its duration.
If the "speaker off" and "speaker on" times are the same, the
resultant waveform is called a square wave and the musical quality is
somewhat hollow, like that of a clarinet. If the "speaker on" and
"speaker off" times are not the same, the waveform is called
"rectangular" and the quality may be saxophone- or oboe-like.
If the "speaker on" and "speaker off" times are programmed to change
randomly, the resultant sound is a pitchless noise.
While any other computer can produce square and rectangular waves,
only those equipped with sound and synthesizer circuits can produce
more complex waveforms. Some sound synthesizers are built on single
integrated circuit chips that can be programmed to produce a wide
variety of waveforms and envelopes. (The envelope of a sound is its
outline as it builds up, sustains and dies out.)
Other synthesizers are built on circuit cards that plug into the
computer or may be completely separate or peripherals. Computer
programs enable musicians to design their own sounds. Musicians think
of this type of programming as "building an instrument": the
"instruments" exist as data that define waveforms and envelopes--and
may therefore be stored in "libraries" on disk or
tape.
Computer-controlled sound synthesizers may be all-digital
(the waveform itself is generated from digital data), all-analog
(waveforms are produced continuously by analog circuitry that responds
to digital instructions) or a combination of the two (waveforms are
converted from digital to analog form, then passed through analog
circuitry). Digital circuits that produce waveforms are made up of
steps that are often audible. Both methods of synthesis have
their advantages and limitations; some musicians prefer the smooth,
distortion-free analog waveforms, while others favor the accuracy and
versatility of digital generators.
PLAYING THE PC
--------------
There are simple programs for most personal computers to make scales
and melodies through the computer's speaker. To use a typical program
of this kind, you type in codes for the pitches and durations of the
notes.
More sophisticated programs enable you to vary the rectangular wave
tone color, adjust the overall tempo, produce trills and glides, and
store tunes that you have programmed on disk or cassette tape.
Music Maker, a software package for the Apple ][, produces the
illusion of two notes being played simultaneously, generates sound
effects as well as musical tones, and displays a colorful animated
video pattern in time with the music. Programs like Music
Maker don't produce complex or high-quality tones; their main uses are
educational and recreational -- you can learn a good deal about
programming, train your ear and have a lot of fun, for a very small
investment in addition to your computer.
By using a computer with a built-in sound synthesizer, or adding a
digitally controlled synthesizer peripheral, you can make music with
a wide variety of interesting tone colors. The Commodore 64 has one
of the most versatile built-in synthesizers of any currently available
personal computer. The "64" uses a proprietary chip that produces
three tones with programmable waveform and envelope. The chip also
contains an analog filter, a device that changes the tone color by
emphasizing some of the sound's overtones and cutting out others.
The resulting range and quality of sound rival that of some of the
analog keyboard synthesizers available in musical instrument stores.
Some of the most musically advanced computer programs are designed
around the Mountain Computer Musicsystem, an eight-voice digital tone
generator for the Apple ][. Among the more popular are the Alpha
Syntauri and the Soundchaser systems. Both use the Musicsystem in
combination with a professional-style four- or five-octave music
keyboard and their own operating software.
With either of these systems you can make up your own sounds, play
them from the music keyboard and record the keyboard performance.
Since one part of the software sets the Musicsystem up to produce the
desired tone colors and another part captures and stores the keyboard
performance, you can play back your keyboard performance with a
variety of tone colors, pitch ranges, and speeds. Both the Alpha
Syntauri and the Soundchaser can implement the basic functions of a
multitrack recording studio. You can record a keyboard performance on
one "track," then play that track back while recording subsequent
tracks. The Syntauri Metatrak program, for instance, lets you
record up to sixteen tracks, then play them back simultaneously. Fast
Forward, Rewind, Record, and Erase functions are implemented by typing
one or two characters on the computer keyboard.
To a musician, using Metatrak (or the Soundchaser Turbotracks program)
is closely akin to using a conventional tape recorder. To the average
computer user, programs that implement a multitrack recorder are
actually file management systems with real-time merging capability.
Whichever way you look at it, Metatrak, Turbotracks, and related
programs offer potent musical resources to pro musicians -- and a lot
of musical enjoyment to amateurs.
In addition to simulating multitrack recorders, computer-based music
systems offer other functions that are important to musicians.
Music-teaching programs are available for both the Soundchaser and the
Alpha Syntauri. Soundchaser's Musictutor package contains an array of
ear-training exercises that not only sharpen your ears, but keep track
of your musical progress.Syntauri's Simply Music program will teach
you how to play a keyboard instrument in a variety of styles and at a
pace that suits you. Once your keyboard chops are in good shape, you
can convert your keyboard performances directly to a printed score
with Syntauri's Composer's assistant, a software package that enables
a dot-matrix printer to produce conventional music
notation.
COMPUTER CONTROL
----------------
The Roland Compumusic CMU-800R is an example of an analog musical
sound generator designed for computer control. The Compumusic uses
electronic piano, organ, and synthesizer circuits to produce
realistic percussion, bass, "rhythm" guitar and melody voices through
your sound system. Using ROland-supplied software, you program the
melody, harmony, and rhythm from the computer keyboard. Then you
"mix" the sounds by manipulating the volume sliders on the Compumusic
unit while the computer "plays" the complete piece of music that
you've programmed. The computer is not able to program the Compumusic
waveforms since these are determined by the unit's analog circuitry.
The advantages of Compumusic are in its high sound quality and
hands-on-the-knobs control.
Musicians have expressed the desire to control a regular electronic
keyboard by means of a computer. An increasing number of electronic
pianos, organs, and synthesizers are being adapted for computer
control. For this purpose, the musical instrument industry has
developed an interface called MIDI, the Musical Instrument Digital
Interface. MIDI allows electronic instruments, computers, and similar
devices to be connected with a minimum of fuss. This means that, if
your computer itself is equipped with a MIDI peripheral and the
necessary software, you can use your computer to control any
MIDI-equipped musical instrument. You can even combine instruments
into a computer-controlled "orchestra."
Will computers ever completely replace human musicians? A number of
traditional instrumentalists, upon seeing entire string and horn
sections replaced by synthesizers and other digital instruments,
have asked this question. The answer lies in the fact that music is
and always will be an aesthetic and emotional experience for humans
and not for computers. There will always be musicians as long as
there is a song in our hearts.
