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.