Electro-acoustic Music: A Primer by Matthew C. Saunders, DMA
Contents:
Some Considerations in the Use of Electro-acoustic Music
Arranging with Electronic Music
For several thousands of years,
there were only five families of musical instruments: the human voice, percussion (striking something),
strings (scraping or plucking something), woodwinds (splitting a stream of air
over an edge) and brass (amplifying vibrations produced by the lips). In the nineteenth and twentieth
centuries, however, a sixth means of musical sound was made possible by the use
of electricity, and later, through the use of electronics. This is known as electro-acoustic music.
Electro-acoustic music is concerned with two primary roles: first, the creation of sound by converting electromagnetic energy into acoustic
energy (sound waves); second, the manipulation
of sound by converting sound waves to electromagnetic energy and performing
some transformation on them before converting them back. These two roles are summarized below,
and are the two component streams of electro-acoustic music.
A. Creation of Sound: (electronische Musik)
B. Manipulation of Sound: (musique concrete)
In
scenario A, there is no pre-existing source for the music that is
produced. This type of composition was
first explored by German composers and engineers working in
In
scenario B, there is some pre-existing sound that is manipulated by electronic
means. The sound may be a musical
sound from the beginning, or it may be a non-musical sound from the world at
large. This type of composition was
first explored by French composers and engineers led by Pierre Shaeffer in the
early 1950s and is frequently referred to by their name, musique concrete, where the term concrete denotes a conglomeration, just as concrete as a building
material is made of many, varied, tiny, but preexisting particles. To my thinking, musique concrete can be as simple as amplification of a single
performer, or as complex as a piece such as Karlheinz Stockhausen’s Hymnen, a two-hour electro-acoustic
piece that is based on the national anthems of several countries. In either situation, a sound that was
originally produced by acoustic means is transformed to electrical energy,
which is then operated on in some way and then turned back into sound. In musique
concrete, the musical expression lies in the original choice of sound, the
means for manipulating that sound, and as always, in the actual construction of
a piece of music.
Some Considerations in
the Use of Electro-acoustic Music
As
an orchestrator or arranger, you will not always have access to the resources
of electro-acoustic music. The
field itself is comparatively young, and orchestras and bands do not have, as a
rule, provisions for the incorporation of electronic resources into their
performances. In addition,
electro-acoustic music is notoriously hard to control in the concert hall, and
it is not uncommon for a piece to sound wonderful in the studio but to fail
miserably in a large hall. Most
conventional venues are not equipped for even high-quality simple playback of
four-channel electronic sound.
However, the creation and control of electronic sound in the recording
studio and on a compositional level is now crucial for work in popular genres,
and the use of digital recording allows a wonderful array of
possibilities. The following
consideration of various electro-acoustic methods should serve as a starting
point, and is by no means exhaustive.
1. Simple
amplification: It is more and more common for
traditional instruments and voices to be amplified. This may be desirable for a piece such
as the Concierto de Aranjuez by Joaquin
Rodrigo in which the classical guitar frequently is difficult to hear against
the orchestra. World-renowned
classical guitarist Sharon Isbin generally amplifies her acoustic instrument
when playing with an orchestra. Her
intent is not to turn a piece for acoustic guitar into a piece for electric
guitar, but rather to allow the rather light sound of her instrument to be
heard in larger halls in competition with a full orchestra. Conventional wisdom would suggest that
as much as possible the original timbre of the instrument should be preserved,
but this may not be the case in new works.
George Crumb’s Black Angels
for amplified string quartet makes use of the microphone’s abilities to
greatly extend the decay of the bowed strings and to create distortion.
2. Complex
amplification: A traditional acoustic instrument or
voice may be not just amplified but processed
by passing the electric signal through one or more filters. This may create
resonance (reverb), alter the tone quality using band-pass filters or even
manipulate pitch. Conversion of the
electric signal to a digital bit-stream is now ubiquitous in recording and
allows effects to be applied at the touch of a button, and then removed if they
do not prove suitable.
3. Specifically
amplified instruments: Some instruments have
“electric” variants that are specifically designed for
amplification and do not work well without it. The most common example is the electric
guitar, in which the metal strings vibrate in a magnetic field, creating an
electrical signal that is converted to sound by an amplifier. The electric piano and electric violin
operate on similar principles. None
of these instruments produces much sound at all in the absence of a functioning
amplifier.
4. Electronic
instruments: Some instruments produce sound by first
creating an electronic tone and then manipulating it in some way.
While the
earliest electronic instruments date from the 1890s, the first important
example is the theremin, from the
1920s, named for its inventor, Leon Theremin. This instrument generates a magnetic
field which the player disrupts with the hands (which have their own magnetic
field). One hand controls pitch and
the other hand controls volume.
This instrument can be heard symbolizing UFOs in many 1950s
science-fiction films, and enjoyed notable uses on the Beach Boys’ album Pet Sounds. The theremin is fairly unique in being
an instrument that the player doesn’t actually touch. Edgard Varese called for two theremins
in his piece Ameriques.
An
important electronic instrument of the 1940s was the ondes martenot, also named for its inventor. This instrument sounds very similar to
the theremin, but is controlled by a piano keyboard. Like the theremin, all notes are
connected by portamento-like glissandi.
Olivier Messiaen called for an ondes martenot in his Turangalila-Symphonie.
Both the
theremin and the ondes martenot were limited to a single timbre, in both cases,
a whistling tone based on the pure sine wave created by their oscillator. By the 1950s, technology had progressed
to a point that allowed the development of the analog synthesizer, an electronic instrument capable of various
timbres by the use of multiple components and electronic settings. Early synthesizers relied on the
technique of additive synthesis, in
which sine or other simple wave forms are layered to create new timbres (all
sounds can, in theory, be expressed as the sum of one or more sine waves; in
practice, it is much more difficult to replicate a given timbre than this makes
it seem). Soon, filters were added to synthesizers,
allowing subtractive synthesis. An interesting use of a bank of filters
creates a device called a vocoder,
which blends two sound sources (think Frampton
Comes Alive). The use of envelope generators soon enabled the
control of attack and decay of individual notes. Additionally, a bank of resonators can be used to allow a single
pulse of sound to create resonances that are then themselves used as timbral
sources.
Early
synthesizers were multi-million dollar machines that filled entire rooms, much
like early computers. Also like
early computers, these machines had only the most basic capabilities. The first commercially viable synthesizer
was the Moog synthesizer, which
featured a piano keyboard to control pitch, and a selection of tone generators,
envelope generators and filters to create musical sounds. The original Moog (pronounced
“moague”) synthesizers were fixed-installed, but were affordable by
individuals and recording studios.
In the late 1960s, the MiniMoog, a simpler, portable version of the Moog
allowed all your favorite rock bands to bring synthesized sound to the stage. Timbre was controlled on all early
synthesizers by a series of patch cables similar to old-fashioned telephone
switchboards. From this usage, we
get the term patch to describe a
specific electronic timbre. Many
listeners were first introduced to electronic sound through Wendy (nee Walter)
Carlos’ album, Switched-On Bach,
featuring the keyboard music of J.S. Bach performed on the Moog synthesizer.
Electronic organs,
such as the Hammond B-3 became very popular during the early 1950s. Many of these were essentially
synthesizers with a limited number of preset timbres (the drawbars on the B-3
and other models). This type of
“organ” became very popular with churches and essentially has
replaced the harmonium.
Beginning
in the 1970s, led by the Yamaha Corporation, the digital synthesizer became the most frequently encountered
electronic instrument. Earlier
synthesizers used electronic components to produce sounds that were analogous
to the activity of the electronics inside, hence their designation as analog electronics. A digital synthesizer creates sound by
referring to a table of numbers and producing sound at a certain volume for
each number. This is also the
underlying principle of digital sound formats such as CDs or MP3s. On CD-quality music, these numbers go by
at a rate of 14,400 per second.
This rate is known as the sampling
rate, and allows accurate reproduction of sounds with frequencies of up to
twice that range, that is, 28,800 Hz, which is well above the range of human
hearing.
A digital
synthesizer has two main parts. The
first is a tone generator, a computer
that has stored within it (or entered into it) the instructions for creating
and reading the wave tables for one or more timbres (or patches). Each available timbre is referred to as
a patch. Some tone generators are
programmable, meaning that the user can develop new timbres by altering the
settings of the tone generator in some way, effectively creating a new wave
table. Other tone generators are
limited to preset patches.
The
second part of a digital synthesizer is a controller
that allows the user to make music using the sounds created by the tone
generator. A controller usually
takes the form of a modified piano keyboard, but other controllers have been
developed over the years as well modeled on instruments. In computer music, it is theoretically
possible to use the computer keyboard as a controller.
A digital
synthesizer may or may not have built-in speakers. For professional settings, it is
generally preferable to link the synthesizer to an external amplifier for more
power.
Up until
the early 1980s, synthesizers from different manufacturers were unable to
communicate with each other; that is, a patch on a Kurzweil machine could only
be played by that machine. Conjure
up an image of the keyboardists from Yes or Emerson,
Part of
the
4. Computer
music: Since the late 1990s, computing power
has become fast enough and cheap enough to create music of high quality on
personal computers. This has led,
as mentioned before, to the near-replacement of traditional tape-based recording
in the studio with digital recording controlled by computer. Much of the same technology is highly
useful to the electro-acoustic composer.
Sampling: Before personal computers became affordable, the Yamaha
Corporation began to incorporate a then-revolutionary capability into many of
their digital synthesizers. Sampling allowed a user to record a
snippet of sound, save it as a wave table and use that sound as the basis for a
new patch. This has led to very
high quality imitations of acoustic instruments which can be controlled by
Sequencing software: A sequencing program (such as Cubase,
Digital Performer or the industry-standard ProTools), allows the user to mix,
edit and move tracks from various sound sources—live performances,
recorded tracks and electronically-generated sources. An idea of the value of sequencing
software can be gotten by a comparison of writing a novel using a typewriter to
writing one using a word processing program. A 32-track mixer can easily be run from
a standard desktop computer with a sufficiently large memory capacity, a far
cry from the mix-down techniques employed during the tape era. Musique
concrete, which traditionally involved literal cutting and splicing of tape
with razor blades, has been rendered, in fact, a much less painstaking task,
and all electro-acoustic music can be controlled through vastly simpler (and
more reliable) means. More
importantly, for the electro-acoustic composer, sequencing software gives a
visual element to the process of electro-acoustic music that is similar to the
traditional score, with various sound sources appearing as a stack of
horizontal tracks, and time progressing from left to right across the computer
screen.
Synthesis software: In addition to having the capability to
record music, computers are now fast enough to produce sound in real time, in
effect simulating digitally the process of creating sound. Software
synthesizers may be plug-ins to sequencing programs or may function as
stand-alone software (or both). The
plug-in versions of these synthesizers can be used to allow real-time
performance of newly designed timbres to be integrated into a project along
with numerous other sources. While
some synthesizers are designed to emulate traditional analog synthesizers (the
Moog is a popular choice because its sounds are by now very familiar to us),
others leave the choices wide open.
An
example of a software synthesizer that is capable of much more is Max/MSP,
which incorporates synthesis, playback of prerecorded files and a wide range of
processing to allow a composer to literally “build” a composition in
a programming environment similar to Visual Basic. Max/MSP also communicates with
Computerized data processing: Computers have
many other possibilities to appeal to the composer. A technique called granular synthesis breaks a sound file into very small (approx. .1
to .01 sec) grains, which are then randomized to create new textures and
timbres (patches have been written for Max/MSP which do this effectively). The use of the Fourier fast transform to determine the component frequencies of a
sound allows the use of spectral music,
in which a sound is reproduced by creating its component frequencies (as in the
music of Tristan Murail and others).
A computer, for example, can take the sound of a clarinet, and break it
into its components (all members of a specific harmonic series). A composer could then assign each of
those frequencies to another instrument and recreate that sound, albeit in a
very different (and hopefully interesting) way. Computer-aided
composition is yet another possibility. For example, a program could be written
in which a composer enters a starting chord, an ending chord and the number of
chords desired in between, and then allows the computer to “write”
the missing sequence of chords. A
program called Open Music was designed for just this sort of application, and
is available as shareware. Since
the beginning of the computer age, programmers have attempted to teach
computers to compose in their own right.
This presumes a system of composition where there are
“right” and “wrong” notes that can be easily predicted. As far back as the mid-18th
century, composers such as C.P.E. Bach and Mozart were able to develop this
type of formulaic, automated composition, since functional tonality lends
itself particularly well to this effort (reasonably simple, fairly few choices
in terms of harmony, reasonably strict formal structures). The first attempts to teach computers to
harmonize simple tunes were fairly successful, but by and large, composition
has been left to the humans. As
artificial intelligence advances, this may not always be the case.
Arranging With Electro-acoustic Music
The
arranger has many considerations when electro-acoustic music is involved. Given that the electronic element may be
as simple as a microphone and an amplifier, it is an area that we all must deal
with. Here are some guidelines:
- Be
as specific as possible and as clear as possible. Many conductors and performers are
not adept with the technology of electro-acoustic music and need it to be
made very clear and very simple.
If a performer is to activate a recorded track during the
performance, it must be clear when, how and who should do so. The provision of a foot pedal to
give a cue to a laptop computer running Max/MSP or some other program is a
fairly simple and more-or-less foolproof means for achieving this.
- Don’t
use an electro-acoustic instrument when a traditional instrument will
achieve the desired effect.
Reserve electro-acoustic means for those situations where nothing
else will do. Traditional
instruments have been refined over hundreds of years, and their technique
and timbre are generally very highly developed and very appealing. An electronic substitute will
generally sound inadequate, clichéd or simply annoying.
- Use
electro-acoustic instruments to achieve that which can’t be done by
traditional means: extremes of
pitch, both high and low, glissandi between these extremes, sampling of
real-world sound sources, manipulation of sound to produce new timbral
effects and the performance of extremely rapid or extremely slow rhythms
are all perfect uses for electro-acoustic music.
- Be
prepared for your music to become rapidly out of date. The technology of music, like all
technology, has moved extremely quickly over the last half-century and
promises to continue to do so.
Take as an example all the music for “tape” produced
since the 1950s—many of these pieces are on reel-to-reel half-inch
tape, and the machines to play them back are becoming rarer and rarer as
digital music has nearly left tape behind, to say nothing of such media as
the eight-track tape, or wire recordings, vinyl analog records of all
varieties, and alternate digital formats such as the Sony MiniDisc,
digital audio tape and Laser Disc.
Even the standard CD may become a rarity one day, and the
near-ubiquitous DVD already shows signs of being superseded by the Blu-Ray
format.
In sixty years, electro-acoustic
composition has moved from a few composers working in specially designed (and
funded) labs using scrounged radio equipment to thousands of composers making
music using nearly any computer (a popular hack has become the original
Nintendo Gameboy, which can be programmed to create electronic music). More importantly, the recording industry
routinely uses techniques developed by composers of electro-acoustic music to
produce popular music. We are
riding a sea change in the way that music is composed, performed and
transmitted, and we do not yet know all the results.
