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Sound Synthesis with Physical Models (1996)

Introduction

“The dynamic behavior of a mechanically produced sound is determined by the physical structure of the instrument that created it” (DePoli 223). The device of production is fundamental to the character of a sound. Nevertheless, most forms of synthesis function without regard to the physical attributes of the sound creation mechanism. Traditional synthesis algorithms take into account primarily the result of sound creation and pay less attention to the control devices that shaped the sound phenomena. More current algorithms, such as additive synthesis, have made use of Fourier analysis and synthesis with a great deal of success. Unfortunately, Fourier techniques are insufficient for the representation of non-pitched material. Physical model synthesis considers the mechanism of a real or imaginary instrument as the focus of the representation. Therefore, a physical model algorithm is capable of recreating aperiodic and transient sonorities produced by the vibrations of the sound creating structure. Scientists and engineers have been making use of physical models for quite some time. In 1971, Hiller and Ruiz were successful in using physical models to create musically useful sounds (Borin 30). Since that time, electronic musicians have explored the creation of sound through the implementation of instrument models. Currently available microprocessors have enabled many composers and performers to make use of physical models with a minimal investment.

Basics of Physical Model Synthesis

Building Blocks

Figure 1 displays a basic two-block scheme for a model. Here it is possible to see the two significant ³building blocks² necessary for physical model synthesis: the exciter and the resonator. Each of these blocks is defined using one of several different approaches (as discussed below).

Black-Box and White-Box Techniques 

The resonator and exciter blocks are described in one of two ways: Black-Box or White-Box. These descriptions give a general idea of the complexity with which a model is constructed. Black box models (FIGURE 2a) are described only by an input and output relationship. The simplicity of the Black-Box model limits the choice of signals that can be involved in the description of the model and makes it difficult to choose the operative conditions of the model (Borin, 31-32). Thus, Black-Box techniques are not entirely useful for synthesis.  White-Box (FIGURE 2b) models describe the entire mechanism of synthesis. Consequently, this synthesis strategy results in a flexible model that is quite difficult to apply and can quickly create a very large number of elements requiring simulation (Borin 32). The masses, springs, dampers, and conditional links described below are only present in a White-Box model; in a Black-Box model they are simply assigned a function.

 Simple Objects

“A model must consider that which is manipulable, deformable, and animated by movements” (Florens 227). The primary objects in a sound-producing model are masses, springs, and dampers. Masses represent the material elements of the instrument, such as wood or brass, while springs and dampers represent linkage elements between the masses. These objects are obviously a substantial simplification to the actual sound creating mechanism, but much simplification is necessary to permit mathematical expressions in a single-dimension to be relatively accurate as well as manageable. Figure 3 shows a simple representation of a sound-producing object as a network.

 The Fourth Object

Using the three elementary objects previously described, the number and variation of available groups or “blocks” is infinite. Nevertheless, these objects cannot fully represent a sound-creating mechanism because they offer no provision for collision with one another. Thus a fourth type of object, the conditional link, becomes necessary. Conditional links are links that are not permanent. They are composed of a spring and a damper and their function is determined by the material that connects them as well as musical circumstance. A conditional link may represent a bow striking a string, the hammers of a piano, or a variety of other temporary excitations.

Physical Model Techniques

Exciters

Before the synthesis of excitation can occur, it is necessary to determine the initial condition of the exciter. At the most fundamental level there exist only two types of initial conditions: those in which only one state of equilibrium exists (percussion), and those in which the exciter begins a new cycle of excitation from a variable equilibrium (bowed and wind instruments). Direct generation Modeling is a black-box technique for those instruments that are persistently excited. This technique may include any system that can generate an excitation signal. The most commonly used example is the table-lookup generator. Direct generation is usually incorporated into feed-forward coupling structures (see below). Memoryless Nonlinear Modeling is a black-box technique often used to model the exciter of wind instruments. This is because it generates an excitation signal that is derived from an “external” input signal that normally incorporates the excitation actions of the performer (FIGURE 4)(Borin 34). This model is also capable of using information that is coming from the resonator. Thus, the resonator’s reaction to an excitation influences the excitations that follow.  Mechanical Modeling is a white-box technique where the exciter is described using springs, masses and dampers (FIGURE 5). Generally, excitations of this type are represented by a series of differential equations that govern the dynamic behavior of these elements (Borin 34). These models can be used to model almost any instrument.

Resonators

“The description of a resonator, without serious loss of generality, is reducible to that of a causal, linear, and time-varying dynamical system” (Borin 35). As with exciters, there are both black- and white-box techniques for modeling resonators. Both techniques can produce surprisingly musical results. Transfer-Function Modeling is a simple, black-box technique that ignores the physical structure of the resonator. The transfer-function model usually implements a transformation of pairs of dual variables, such as pressure and flow or velocity and force (Borin 35). Because this resonator is such a generic device, it is not the most musically useful resonator model. Mechanical Modeling of the resonator is very similar to mechanical modeling of the exciter. A series of differential equations are used to simulate the dynamic behavior of virtual masses, springs, and dampers. Waveguide Modeling is an efficient technique that is based on the analytic solution of the equation that describes the propagation of waves in a medium. For example, the waveguide model of the reed of a wind instrument requires only one multiply, two additions, and one table lookup per sample of synthesized sound (Smith 275). Because of the small number of simulations that it requires, this technique was the first to be incorporated into commercially available synthesizers.

Interaction

Just as there are several strategies for modeling exciters and resonators, there are numerous methods for controlling the interaction between the blocks. The Feed-forward technique (FIGURE 1) is the simplest structure by which exciter and resonator may be coupled. The transfer of information is unidirectional which prevents the excitation from being influenced by the resonance. “This structure lends itself particularly well for describing those interaction mechanisms in which the excitation imposes an initial condition on the resonator and then leaves it free to evolve on its own, or in which the excitation can be treated as a signal generator” (Borin 37). The Feedback technique (FIGURE 6) is a slight variation on feed-forward. The transfer of information is bi-directional and permits the modeling of most traditional instruments where a vibratory structure is influenced.

The most sophisticated interaction scheme, which is also the most computationally complex, is the Modular Interaction method. This model incorporates an interconnection block (FIGURE 7). The interconnection block acts as an interface; its main purpose is to separate the excitation from the resonator, so that they can be designed independently (Borin 38). Thus, the third blacks becomes the master of the information exchange between the exciter and the resonator.

Current Hardware and Software Developments

CORDIS/ANIMA

The CORDIS/ANIMA system is designed for the mechanical simulation of physical models. The CORDIS system originally ran on the LSI-11 type microcomputer from Digital Equipment Corporation. The system is capable of decomposing all aspects of the model into the most basic elements: masses, springs, and dampers. In 1985, the ANIMA update to CORDIS allowed modeling of two- and three-dimensional elements. This system was the first to fully incorporate conditional links.

Csound

Csound is a music programming language for IBM-compatible, Apple Macintosh, Silicon Graphics, as well as several other computers. It was written by Barry Vercoe at the MIT Media Lab. The programmer is required to give Csound an “Orchestra” file using an infinite number of instruments and instrument parameters, and a “Score” file that may be equally as complex. Csound then creates a soundfile containing the completed work.

A typical Csound “Orchestra” specification using the Karplus-Strong pluck algorithm:

; timbre: plucked string
; synthesis: Karplus-Strong algorithm(15)
; PLUCK with imeth = 1 (01)
; pluck-made series(f0) versus
; self-made random numbers(f77) (1)

sr = 44100
kr = 441
ksmps= 100
nchnls = 1

instr 1;
iamp = p4
ifq = p5 ; frequency
ibuf = 128 ; buffer size
if1 = 0 ; f0: PLUCK produces its own random numbers
imeth = 1 ; simple averaging

a1 pluck iamp, ifq, ibuf, if1, imeth
out a1
endin

instr 2;
iamp = p4
ifq = p5 ; frequency
ibuf = 128 ; buffer size
if1 = 77 ; f77 contains random numbers from a soundfile
imeth = 1 ; simple averaging

a1 pluck iamp, ifq, ibuf, if1, imeth
out a1
endin

A “Score” written for this particular “Orchestra”:

; GEN functions
; “Sflib/10_02_1.aiff” should exist
f77 0 1024 1 “Sflib/10_02_1.aiff” .2 0 0 ; start reading at .2 sec
; score
; iamp ifq
i1 0 1 8000 220
i1 2 . . 440
i2 4 1 8000 220
i2 6 . . 440
e

Many composers working with physical models currently use Csound. The power of the program to control even the smallest nuance of a soundfile, as well as the ability to import sampled sounds, and the convenience of recycling sophisticated “Orchestras” and “Scores”, make it a powerful physical modeler.

Conclusion

Physical modeling is a very powerful form of synthesis. Each of the techniques outlined above, whether they be recreations of general sound-production mechanisms, or an attempt at an exact reference to one specific instrument, provides a composer with an opportunity to expand his or her sonic “palette.”  “It can be argued that often behind the use of physical models we find the quest for realism and naturalness, which is not always musically desirable. On the other hand we can notice that even with a physical model it is easy to obtain unnatural behaviors, by means of few variations of the parameters. Moreover, the acquired experience is useful in creating new sounds and new methods of signal organization” (DePoli 225).   Physical models provide insight into the function of the instruments that composers have been working with for centuries. Perhaps gaining a better understanding of acoustic instruments, as well as developing systems that can accurately model them, will enable electronic musicians to create more dynamic, more deeply evolving timbres than previously thought possible.

References

Adrien, Jean-Marie. 1991. “The Missing Link: Modal Synthesis.” Representations of Musical Signals. Cambridge, Massachusetts: MIT Press, pp. 269-297.

Borin, Gianpaolo, et al. 1992. “Algorithms and Structures for Synthesis Using Physical Models.” Computer Music Journal 16(4):30-42.

DePoli, Giovanni. 1991. “Physical Model Representations of Musical Signals: Overview.” Representations of Musical Signals. Cambridge, Massachusetts: MIT Press, pp. 223-226.

Florens, Jean-Loup, and Cadoz, Claude. 1991. “The Physical Model: Modeling and Simulating the Instrumental Universe.” Representations of Musical Signals. Cambridge, Massachusetts: MIT Press, pp. 227-268.

Keefe, Douglas H. 1992. “Physical Modeling of Wind Instruments.” Computer Music Journal 16(4):57-73.

Smith, Julius. 1986. “Efficient Simulation of the Reed-Bore and Bow-String Mechanisms. “Proceedings of the 1986 International Computer Music Conference.” San Francisco: Computer Music Association.

Smith, Julius. 1992. “Physical Modeling Using Digital Waveguides.” Computer Music Journal 16(4):74-91.

Woodhouse, James. 1992. “Physical Modeling of Bowed Strings.” Computer Music Journal 16(4):43-56.

Granular Synthesis (1995)

Introduction

“Granular synthesis is an innovative approach to the representation and generation of musical sounds” (DePoli 139). The conception of a granular method of sonic analysis may have been first proposed by Isaac Beekman in his article Quantifying Music (Cohen). This late Nineteenth Century document discusses the organization of music into “corpuscles of sound”. Unfortunately, granular synthesis theory was not investigated further for quite some time. British physicist Dennis Gabor stimulated new interest in granular synthesis around 1946 (Gabor). Gabor believed that any sound could be synthesized with the correct combination of numerous simple sonic grains. “The grain is a particularly apt and flexible representation for musical sound because it combines time-domain information (starting time, duration, envelope shape, waveform shape) with frequency domain information (the frequency of the waveform within the grain)” (Roads 144). Before magnetic tape recorders became readily accessible, the only way to attempt granular composition was through extremely sophisticated manipulation of a large number of acoustic instruments (as in many of the early compositions of Iannis Xenakis). The tape recorder made more sophisticated granular works possible. However, the laborious process of cutting and splicing hundreds of segments of tape for each second of music was both intimidating and time-consuming. Serious experimentation with granular synthesis was severely impaired. It was not until digital synthesis that advanced composition with grains became feasible.

Basics of Granular Synthesis

The grain is a unit of sonic energy possessing any waveform, and with a typical duration of a few milliseconds, near the threshold of human hearing. It is the continuous control of these small sonic events (which are discerned as one large sonic mass) that gives granular synthesis it’s power and flexibility. While methods of grain organization vary tremendously, the creation of grains is usually relatively simple. A basic grain generating device would consist of an envelope generator with a gaussian curve driving a sine oscillator (figure 1). The narrow bell-shaped curve of the gaussian fill is generated by the equation: The signal from the oscillator enters an amplifier that determines spatial position of each grain. Quadraphonic amplification is very popular for granular synthesis because of the great spatial positioning capabilities. The typical duration of a grain is somewhere between 5 and 100 milliseconds. If the duration of the grain is less than 2 milliseconds it will be perceived as a click. The most musically important aspect of an individual grain is its waveform. The variability of waveforms from grain to grain plays a significant role in the flexibility of granular synthesis. Fixed-waveforms (such as a sine wave or saw wave), dynamic-waveforms (such as those generated by FM synthesis), and even waveforms extracted from sampled sounds may be used within each grain. A vast amount of processing power is required to perform granular synthesis. A simple granular “cloud” may consist of a only a handful of particles, but a sophisticated “cloud” may be comprised of a thousand or more. Real-time granular synthesis requires an endless supply of grain generating devices. Several currently available microcomputers are capable of implementing real-time granular synthesis, but the cost of these machines is still quite prohibitive. Therefore, most granular synthesis occurs while the composer waits, sometimes for quite a while. This time factor prevents many electronic and computer composers from working with granular synthesis.

Methods of Grain Organization

Screens

One of the first composers to develop a method for composition with grains was Iannis Xenakis. His method is based on the organization of the grains by means of screen sequences (figure 2), which specify the frequency and amplitude parameters of the grains (FG) at discrete points in time (Dt) with density (DD) (DePoli 139). Every possible sound may therefore be cut up into a precise quantity of elements DF DG Dt DD in four dimensions. The scale of density of grains is logarithmic with its base between 2 and 3, and does not exist on the screens. When viewing screens as a two dimensional representation, it is important not to lose sight of the fact that the cloud of grains of sound exist in the thickness of time Dt and that the grains of sound are only artificially flattened on the plane (FG) (Xenakis 51). Xenakis placed grains on the individual screens using a variety of sophisticated Markovian Stochastic methods which he changed with each composition. The first compositions to use this method were Analogique A, for string orchestra, and Analogique B, for sinusoidal sounds, both composed in 1958-59. More recently, a variation on Xenakis’ screen abstraction has been implemented into the UPIC workstation discussed below.

Pitch-Synchronous Granular Synthesis

Pitch-synchronous granular synthesis (PSGS) is an infrequently performed analysis-synthesis technique designed for the generation of pitched sounds with one or more formant regions in their spectra (Roads 191). It makes use of a complex system of parallel minimum-phase finite impulse response generators to resynthesize grains based on spectrum analysis.

Quasi-Synchronous Granular Synthesis

Quasi-synchronous granular synthesis (QSGS) creates sophisticated sounds by generating one or more “streams” of grains (figure 3). When a single stream of grains is synthesized using QSGS, the interval between the grains is essentially equal. The overall envelope of the stream forms a periodic function. Thus, the generated signal can be analyzed as a case of amplitude modulation (AM) (Roads 151). This adds a series of sidebands to the final spectrum. By combining several QSGS streams in parallel it becomes possible to model the human voice. Barry Truax discovered that the use of QSGS streams at irregular intervals has a thickening effect on the sound texture. This is the result of a smearing of the formant structures that occurs when the onset time of each grain is indeterminate.

Asynchronous Granular Synthesis

Asynchronous granular synthesis (AGS) was an early digital implementation of granular representations of sound (figure 4). In 1978, Curtis Roads used the MUSIC 5 music programming language to develop a high-level organization of grains based on the concept of tendency masks (“Clouds”) in the time-frequency plane (DePoli 140). The sophisticated software permitted greater accuracy and control of grains. When performing AGS, the granular structure of each “Cloud” is determined probabilistically in terms of the following parameters:

1. Start time and duration of the cloud
2. Grain duration (Variable for the duration of the cloud)
3. Density of grains per second (Also variable)
4. Frequency band of the cloud (Usually high and low limits)
5. Amplitude envelope of the cloud
6. Waveforms within the grains
7. Spatial dispersion of the cloud

Obviously, AGS abandons the use of specific algorithms and streams to determine grain placement with regard to pitch, amplitude, density and duration. The dynamic nature of parameter specification in AGS results in extremely organic and complex timbres.

Some Recent Hardware and Software Developments

The UPIC Workstation

UPIC (Unite Polyagogique Informatique du CEMAMu) is a machine dedicated to the interactive composition of musical scores (Xenakis 329). It was conceptualized by Xenakis and created at the CEMAMu (Centre for Studies in the Mathematics and Automation of Music) in Paris. The UPIC software consists of pages on which a composer draws “arcs” which specify the pitch and duration of a sonic event (figure 5), and a voice editing matrix with which the “arcs” are described. Waveform, envelope, frequency and amplitude tables, modulating arc assignment, and modification of audio channel parameters (dynamic and envelope) may all be manipulated for each “arc” in real-time.

The hardware of the UPIC system consists of a Windows-based computer with a digitizing tablet, and the UPIC Real-Time Synthesis Unit:

64 Oscillators at 44.1 kHz with FM converter board:

  • 4 audio output channels
  • 2 audio input channels
  • AES/EBU interface

Capacity:

  • 4 pages of 4000 arcs
  • 64 waveforms
  • 4 frequency tables
  • 128 envelopes
  • 4 amplitude tables

The UPIC Workstation is ideal for granular synthesis for several reasons. First, it allows any waveform (including sampled waveforms) to be assigned to each “arc”. Second, it currently permits 64 “arcs” to be layered vertically. This enables the composer to design “clouds” of sound up to 64 grains in density and of infinite duration at any point in a composition. Finally, and perhaps most importantly, the UPIC requires no time to process any of its functions.

Csound

Csound is a music programming language for IBM-compatible, Apple Macintosh, Silicon Graphics, as well as several other computers. It was written by Barry Vercoe at the MIT Media Lab. The programmer is required to give Csound an “Orchestra” file using an infinite number of instruments and instrument parameters, and a “Score” file which may be equally as complex. Csound then creates a soundfile containing the completed work.

A typical Csound granular “Orchestra” specification:

;;; granulate.orc

sr=44100
kr=22050
ksmps=2
nchnls=1

instr 1
next: timout 0,p6,go1 ;;; p6 = grain duration time… I could allow for an envelope on this
reinit go1
timout 0,p5,go2 ;;; p5 = inter-grain time… I could allow for an envelope on this
reinit next

go1:
k1 oscil1i 0,1,p6,3
a1 soundin p7,p4,4 ;;; p7 is which soundin file to use…
a2 = a1 * k1
rireturn
go2:
k2 oscil1i 0,1,p3,4 ;;; envelope output sound.
out a2*k2
endin
;;Copyright 1992 by Charles Baker

A “Score” written for this particular “Orchestra”:

;; sample .sco file
f 3 0 8193 9 1 -.5 90 0 .5 90 ;; grain envelope
f 4 0 8193 9 1 -.5 90 0 .5 90 ;; Note amplitude env.
;;ins st dur amp inter-grain-time grainduration soundinfile#
i 1 0.000 2.750 1 0.000 0.020 1
i 1 2.750 2.612 1 0.010 0.020 1
i 1 5.362 2.482 1 0.020 0.020 1
i 1 7.844 2.35
i 1 0.030 0.020 1
i 1 10.202 2.240 1 0.04 0.020 1
i 1 12.442 2.128 1 0.05 0.020 1
i 1 14.570 2.022 1 0.06 0.020 1
i 1 16.591 1.920 1 0.07 0.020 1
i 1 18.512 1.824 1 0.08 0.020 1
e
;;Copyright 1992 by Charles Baker

Many granular composers currently use Csound. The power of the program to control even the smallest nuance of a soundfile, as well as the ability to import sampled sounds, and the convenience of recycling sophisticated granular “Orchestras” and “Scores”, make it a powerful granular synthesizer.

Cloud Generator

Cloud Generator is a granular synthesis application for the Apple Macintosh (figure 6) . The software was conceived and programmed by Curtis Roads and John Alexander at Les Atelier UPIC in Paris. Cloud Generator creates clouds using Quasi-Synchronous or Asynchronous Granular Synthesis based on the parameters listed in that section on AGS above . Each QSGS stream and AGS “Cloud” must be created individually and is output in AIFF format.

Conclusion

Granular synthesis is a very powerful means for the representation of musical signals. Each of the techniques outlined above provides an opportunity for a composer to expand his or her sonic “palette”. Asynchronous Granular Synthesis is a particularly powerful means for creating sonic events that are both unique and sophisticated. “In musical contexts these types of sounds can act as a foil to the smoother, more sterile sounds emitted by digital oscillators” (Roads 183). When granular synthesis techniques are used in conjunction with sampled waveforms, the possibilities for new sounds are infinite.

References

Cohen, Michael, ed. Isaac Beekman. Dordrecht, The Netherlands: D. Reidel, 1990.

DePoli, Giovanni, ed. Representations of Musical Signals. Cambridge, Massachusetts: The MIT Press, 1991.

Gabor, Dennis. “Theory of Communication.” Journal of the Institute of Electrical Engineers Part III, 93: 429-457.

Roads, Curtis. “Asynchronous Granular Synthesis.” Representations of Musical Signals. Cambridge, Massachusetts: The MIT Press, 1991.

Strange, Allen. Electronic Music: Systems, Techniques and Controls. Dubuque, Iowa: W.C. Brown Company, 1983.

Truax, Barry. “Real-time granular synthesis with a digital signal processor.” Computer Music Journal 12(2): 14-26.

Xenakis, Iannis. Formalized Music. Stuyvesant, NY: Pendragon Press, 1991.

A Brief History of Computer Music (1994)

“I dream of instruments obedient to my thought and which with their contribution of a whole new world of unsuspected sounds, will lend themselves to the exigencies of my inner rhythm.” (Hansen, 316) When Edgard Varese spoke these words in 1937, he had no idea that he was presaging one of the greatest movements in modern musical history: Computer Music. While the importance of taped and analogue electronic music is not to be underestimated, the invention and dissemination of the digital system (whether in microcomputer, instrument, or hybrid form) is the greatest single step in the realization of Varese’s dream. If only he had lived to see his dreams come to fruition! Like many composers throughout music history, Varese was tired of the tonal, textural, and timbral capabilities of acoustic instruments. Even the acoustic music purists yearned for the ability to realize a work immediately. The only way to hear a multi instrument piece before the advent of electronic instruments was to have an orchestra close at hand, a very costly and inefficient solution that could only be afforded to the very wealthy or the very famous. These capabilities (and many more that were never considered possible) are now available to almost any composer with a minimum of obtainable funds and space. Of course, the mostly digital system of today has been a long time in the making.

In the half century prior to 1945 (a date recognized by most modern music scholars as the beginning of the electronic era) there seemed to be a sort of lull in the development of new musical instruments. “Innovations in new musical technology, especially the creation of new instruments…have been a normal feature of Western musical history, moving hand in hand with the expansion of compositional resources. Such parallel development is understandable, since extensions in musical language often require new instruments for adequate realization…” (Morgan, 461). While extensions in musical language had flourished throughout the end of the 19th century and beginning of the 20th (Romanticism, Impressionism, Expressionism, chromaticism, atonality, serialism, and chance composition all being excellent examples) the development of new instruments seemed to come to a standstill. That is not to say that new instruments were not invented during this period, but none with the capabilities necessary to complement the new compositional developments. For instance, there is a surprising entry in the records of the United States patent office dated 1897. The patent, registered in the name of Thaddeus Cahill, describes an “electrically based sound generation system, subsequently known as his Dynamophone or Telharmonium, the first fully developed model being presented to the public in 1906…” (Manning, 1). When the proportions of the device are considered, 200 tons in weight and nearly 60 feet in length, it is easy to see why this invention passed into obscurity. It is slightly more difficult to understand the enigmatic demise of such devices as Lev Termen’s Theremin (1924), capable of performing a continuous range of pitches by altering the frequency of an electronic oscillator, Maurice Martenot’s ondes martenot (1928), also capable of continuous frequency range, but with improved pitch control and greater timbral variety, and the Trautonium (1930), a keyboard controlled instrument. These instruments were all capable of creating sounds that were previously unimaginable. Why then did these first electronic inventions fail? For two reasons. First, all of these “instruments were quite primitive in both construction and sound producing capacity. Moreover there was as yet no efficient means for storing, transforming, and combining sounds.” (Morgan, 462) More importantly, the music world was not quite ready for instruments that so radically changed the traditional concept of the musical instrument. Even the ground breaking composers remained committed to the equal tempered Western pitch system and the traditional musical instruments. “While the above devices concern the electronic synthesis of sound, other pre-1945 activities focused on the electronic manipulation of sounds already extant.” (Schwartz, 109) In the 1930’s the electric phonograph was frequently employed for compositional and performance purposes. Several important composers took advantage of this new medium: Paul Hindemith, Ernst Toch and Darius Milhaud were some of the earliest experimenters. All three used variable speed turntables capable of creating distortion and remarkable collage effects. Varese used the turntable to compose a series of very noisy compositions of great originality, but stopped composing around this time because he was no longer interested in seeking sound from conventional instruments. In John Cage’s Imaginary Landscape No. 1 (1931) a variety of turntable speeds were used to manipulate laboratory test signals, and the results were mixed with muted piano and cymbal for live radio broadcast. The work of these composers and their use of nontraditional instrumentation was beginning to gain widespread acceptance. More importantly, these early attempts at composition using mechanical instruments paved the way for the transpiring electronic advancements.

Although the major advancements in electronic and computer music occurred primarily in the United States, the first steps were taken almost simultaneously in France and Germany. The analogue tape recorder had been perfected by this time, and it played a substantial part in the creation and distribution of music from this point forward. In 1948 a young engineer for French National Radio, Pierre Schaeffer, began producing taped recordings of natural sounds. These included locomotive sounds, wind, thunder, and a variety of others. More importantly, the sounds were transformed in several ways. “The transformational included editing out portions of the sound, varying the playback speed, playing the sounds backward (tape reversal), and combining different sounds (overdubbing).” (Morgan, 463). Schaeffer first performance of his work, in Paris in October of 1948, was significant because it was the first public performance of music that was not played by humans. This music was entitled musique concrete, because the sounds were concrete, sonorous objects that could be plastically manipulated, and not “abstract.” The West German Radio Corporation was the location of similar experiments at roughly the same time. The works composed here by Herbert Eimert and Werner Mayer-Epper had a decidedly experimental slant. The composers were less interested in creating atmospheric sounds (like Schaeffer) and more concerned with studio created sounds. Several extremely important new sounds were recorded: the first, a simple sine tone, free from overtones, produced by an electric oscillator. “The Cologne studio also had noise generators (capable of producing a thick band of frequencies within a given range), ring modulators, filters, and reverberators. The ring modulators allowed one tone to modulate the amplitude of another, producing complex sidebands (sum and difference tones), and the resulting sonority could then be filtered to control timbres.” (Schwartz, 113) Here were the true beginnings of electronic music! The verification of the importance of these new discoveries is provided by Karlheinz Stockhausen. After a year long visit to Paris where he worked with Schaeffer in the French studio, Stockhausen returned to his home, Cologne. The works he composed during this period, Elektronische Studien I and II (1953 and 1954), were the first uses of these technologies in compositions of a more intellectual approach. (Studie II was, in fact, the first electronic composition to be formally notated.) The upper section of Studie II (see figure 1), calibrated from 100 to 17,200 refers to pitch and timbre. The individual pitches used in this composition are chosen from a scale of 81 steps with a constant interval ratio of 25\/5 and 193 mixtures constructed from them. The heavy horizontal lines indicate the high and low frequencies of the first sound mixture, to which another overlapping mixture is added. The two horizontal lines in the middle of the page indicate the duration of the sounds in terms of centimeters of tape moving at specified speed. The triangular shapes at the bottom indicate volume in decibels. Not long after the publication of this work the term musique concrete became synonymous with the more popular term “electronic music” and by the late 1950s fell from popular usage. This was probably due to the rapidly increasing popularity of all things electronic. The recognition gained by the works of Stockhausen, as well as interest in the instruments which he had exploited in their production, had a profound influence on worldwide research combining music and technology. Edgard Varese, excited by the prospect of new sonic potential, accepted an invitation from Schaeffer to come to Paris and resume composing. This was primarily due to a lack of comparable facilities in America. The results of this foray were not wholly satisfactory, a combination perhaps of three factors: the relatively short period spent in preparation, the limitations of the equipment, and the immense practical problems which confront any composer encountering a complex studio for the first time. (Manning, 92) Nevertheless, Varese produced Deserts, and in doing so attracted a considerable amount of attention to electronic music. The first major presentation of Varese’s new body of work took place on 30 November, 1955, at Town Hall, New York. “This work could not have occurred at a more appropriate time, for the interest of institutions in supporting electronic music was just being kindled.” (Manning, 93) The Rockefeller Corporation paved the way for an increase in research by providing funding for an investigation into the state of studio facilities in the US and overseas. The investigators found that the studios abroad were well advanced. In sharp contrast, very limited progress had been made in America during this time. The investigators did find that several American institutions were attempting to use computers for musical composition, but with only moderate success. The most important research of this period (unbeknownst to the electronic musicians of the time) was a project that had begun at Bell Telephone Laboratories, New Jersey, that would lead to the first digital synthesizer. Nevertheless, the investigators were disturbed by the lack of research possibilities in America. This lack of promise was the force that drove the investigators, Luening and Ussachevsky, to take the initiative and approach the authorities of Columbia University with plans for an electronic music research facility. Their proposal met with favorable response and a grant was awarded. Soon thereafter, upon completion of their investigation of studios worldwide, the men received a grant for $175,000 from the Radio Corporation of America. RCA wanted Luening and Ussachevsky to use their facility as the basis for a Columbia-Princeton Electronic Music Center. Here the first analog synthesizer (creatively titled the RCA synthesizer) was developed (1959). Quickly thereafter, the Mark I and Mark II RCA synthesizers were developed.

Figure 1 – An Excerpt from the Score for Stockhausen’s Studie II

Research in the US escalated and a variety of institutions (mostly academic) took an active part in computer music research. One of the first composers to take advantage of the new RCA equipment was Milton Babbitt. Babbitt’s first electronic work, Composition for Synthesizer (1961), was the fruit of a seemingly effortless transition from his strictly ordered style of instrumental writing to an electronic equivalent. (Manning, 113) These machines eliminated not only the need for tape manipulation but also for the laborious task of interconnecting numerous electronic components: “For Babbitt, the RCA synthesizer was a dream come true for three reasons. First, the ability to pinpoint and control every musical element precisely. Second, the time needed to realize his elaborate serial structures were brought within practical reach. Third, the question was no longer “What are the limits of the human performer?” but rather “What are the limits of human hearing?” (Schwartz, 124) The publicity accorded to the Columbia/Princeton Facility by the presence of Babbitt and numerous others (Ussachevsky, Luening, Dabh, and Berio to name a few) increased the interest in electronic music even further. The introduction of the voltage controlled synthesizer in the mid 1960’s was the result of research at numerous institutions and commercial research. Dr. Robert Moog (Moog), probably the best known synthesizer developer, Donald Buchla (Buchla), Paul Ketoff (SynKet), and the Arp Corporation all introduced voltage controlled, often keyboard oriented synthesizers at around the same time. The commercial potential of these small, portable, simplified systems was tremendous.

As the 60’s came to a close, a number of key composers did much to further the cause of electronic music. The electronic instruments of this time were monophonic; that is, capable of producing single melodies which had to be recorded and combined with other recorded melodies to make music. In this manner, complex textures could be obtained by the combination of several different melodic or rhythmic lines. (Hansen, 362) Varese, Stockhausen, and Babbitt remained prominent in the field and a variety of newcomers to electronic techniques, Cage, Subotnick, and especially Carlos, who made the term “synthesizer” a household word, helped to augment the expanding library of electronic works. Morton Subotnick’s work was the first to take full advantage of the capabilities of these smaller synthesizers. Silver Apples of the Moon (1967) was the first newly composed work relying on voltage control to gain widespread attention and the first such work intended specifically for recording. (Schwartz, 126). The piece was commissioned by Nonesuch Records and realized on a Buchla synthesizer. This was followed by several other recorded works including The Wild Bull (1968) and Touch (1969). John Cage used these new instruments in his legendary collaborations with the dancer and choreographer Merce Cunningham (throughout the 1960s). Wendy Carlos provided the most dramatic impetus to public acceptance with the phenomenal success of Switched On Bach(1968), a commercial recording featuring virtuosic arrangements for Moog synthesizer of compositions by J.S. Bach. (Morgan, 470) Even during this time of great compositional resourcefulness, many composers longed for further developments. The primary concern of this contingent was an artificiality of sound that was difficult to avoid with these analogue instruments. Fortunately, looking just a few years ahead, it was possible to see an almost separate revolution in the making: the birth of the digital system. “Although computer music was born in the 1950s, it was not until the mid-1970s that digital technology began to rival concrete techniques and voltage controlled synthesis in widespread usage. The decades that followed saw an exponential growth in computer science and an equally remarkable expansion of its musical applications.” (Schwartz, 135)

In order to understand the state of computers and digital systems in the 1970s it is first necessary to look to the 1950s. In 1957 Max Mathews, then an engineer at the Bell Telephone Laboratories in New Jersey, began experimenting with the computer to generate and manipulate sound. It was at this lab that the first computer program capable of sonic manipulation was developed. It was entitled MUSIC4. By today’s standards, the mainframe computer on which Mathews’ program ran was big, awkward, slow and extremely expensive to operate. In spite of all this, several composers were enthusiastic about this new development. James Tenney, Godfrey Winham, Hubert Howe, J.K. Randall, Gottfried Michael Koenig, and Barry Vercoe all worked with Mathews’ system. A few years later Howe, Randall, and Windham started a computer music facility at Princeton University using a modified version of MUSIC4 running on an IBM mainframe. Eventually Max Mathews left Bell Labs for Stanford. By the mid-1960s research had shifted from the large corporations to the major universities of America. Leading the way were Princeton and Stanford (of course), and the University of Illinois. At the same time that Max Mathews was experimenting with computer generated sound, University of Illinois scientist and composer Lejaren Hiller was using the computer to a very different end. “… Hiller postulated that a computer could be taught the rules of a particular style and then called on to compose accordingly.” (Schwartz, 347) Hiller’s first piece was entitled Illiac Suite (1957) for string quartet. Although not entirely successful, this work served to further research regarding artificial intelligence and computer assisted composition. “The foregoing would seem to imply that Europe played no important role in the first two decades of computer music, and indeed,…little happened there until 1969.” (Schwartz, 350) It was during this year that Frenchmen Jean Claude Risset and Pierre Boulez joined together to battle the skepticism on that continent toward computer music. The French government eventually conceded and by 1976 IRCAM was founded: “A vivid indication of the growing importance of computer technology in the field of contemporary music is provided by the Institut de Recherche et de Coordination Acoustique/Musique in Paris. …Under the general direction of Pierre Boulez and funded by the French government, IRCAM is a large and active research organization devoted to the scientific study of musical phenomena and to bringing together scientists and musicians to work on common interests.” (Morgan, 477). From then until the present, IRCAM has remained one of the most prestigious and richly endowed centers for computer music research and composition in the world, and one of the few not aligned with a university. (Schwartz, 350) Composers from all over the world have worked there including John Chowning, and Max Mathews. While research dealing with the computational and sound generating capabilities of computers was booming, development of instruments had taken a back seat.

As the 1970s concluded and computers became smaller, faster, and cheaper, emphasis was redirected toward the development of instruments that utilized this improved technology. “The work of John Chowning at Stanford has proved particularly significant in this context.” (Manning, 223). During the late 1960s Chowning had been experimenting with frequency modulated sound (the same technique utilized by radio and television operators to transmit noise (called free signals). His discoveries were exciting but not commercially viable at the time. After evaluating his discovery and two of his subsequent compositions the Stanford authorities, apparently more interested in commercially viable professors, turned down his application for tenure! The calculations required to perform FM synthesis were so complex that most US instrument manufacturers couldn’t understand the concept, much less see the viability of mass production. It wasn’t until the late 1970’s that a firm was willing to commercially market FM. That firm was Yamaha. “Turning FM synthesis from a software algorithm that ran on mainframes into chips that powered a commercial synthesizer took seven years.” (Johnstone, 58) From the Yamaha point of view, the wait paid off. In 1983, Yamaha introduced the first stand alone digital synthesizer, the DX-7. Priced under $2000 the keyboard was a huge success, selling more than 200,000 units, ten times more than any synthesizer before or since. Just prior to the release of the DX-7, a group of musicians and music merchants met to standardize an interface by which new instruments could communicate control instructions with other instruments and the prevalent microcomputer. This standard was dubbed MIDI (musical instrument digital interface). “This important communications standard, the result of an agreement reached by all major manufacturers in 1983, has made it possible to adopt a modular approach to the construction of comprehensive mixed digital systems, easily expanded to accommodate new developments.” (Manning, 257) The electronic composer was now provided with not only an inexpensive instrument, but also the capacity to control it. “This technology allows a single keystroke, control wheel motion, pedal movement, or command from a microcomputer (e.g., an Apple Macintosh) to activate every device in the studio remotely and in synchrony, with each device responding according to conditions predetermined by the composer.” (Schwartz, 359) Thus, Varese’s dream for absolute control had finally been achieved. A single individual could now control an entire studio worth of gear without getting out of her/his seat. Moreover, with easily acquired software, note sequences played on a keyboard or other MIDI capable instrument could be digitally recorded and played back by the computer. These sequences could then be easily stored and randomly accessed at a later date. Numerous useful programs were soon developed for compositional purposes. The most important of these is probably MAX, an object oriented music programming environment capable of a variety of “artificially intelligent” processes. It was developed at IRCAM specifically for the Apple Macintosh series of computers by programmer Miller Puckette and later refined by David Zicarelli. “Perhaps the only MIDI resource ideally suited to experimental composition, MAX allows even musicians with no programming expertise to create an infinite variety of custom made MIDI output devices and routines using simple on-screen graphic displays. One can continually invent and reinvent a studio full of phantom hardware at will, limited only by the composer’s imagination.” (Schwartz, 361)

The final result of the new developments in computer music is the ability for the computer to participate in live performance. Electronic works could now be performed precisely in a live setting and interaction with human performers was effortless. A new wave of compositions, written by composers most of whom grew-up with some semblance of synthesizers and computers surrounding them, utilize MIDI and programs such as MAX to realize a vast array of new ideas. Furthermore, a variety of new instruments have been developed. Gary Nelson, codirector of the TIMARA (Technology in Music and the Related Arts) program at Oberlin College, developed the MIDI horn in 1985. This instrument, which made no sound of its own, was interfaced with a DX-7 and provided breath control of volume and a familiar key layout that almost any woodwind player could manipulate with a minimum of practice. In a slightly different vein, Dexter Morrill, a Colgate University Professor of Music, developed a computer program that could recognize the pitches of an acoustic instrument. His program (written in the artificial intelligence language, LISP) could reroute incoming MIDI data to synthesizers and effect boxes, allowing a solo instrumentalist to sound like a complete orchestra. Morrill’s Sketches for Invisible Man (1989) employed this technique, allowing the performer to improvise while the computer provided intelligent accompaniment. Morton Subotnick quickly became one of the most avid proponents of real-time interactive composition. (Schwartz, 363) His work Hungers (1987) takes advantage of an entire studio worth of MIDI equipment. In this work, all of the equipment is controlled by a series of MIDI commands from a Macintosh computer. The computer responds to live input from a MIDI keyboard. Another work, In Two Worlds (1987) was written for solo saxophone, orchestra and WX-7 (Yamaha’s sax-like MIDI controller). Here the computer serves as the orchestra, reacting to a MIDI Baton wielded by the conductor just like a real orchestra. “Still in the forefront of computer music research, Max Mathews has updated his concept with his Radio Drum; stick movements are sensed by antennae and converted to MIDI signals, whose effects on electronic instruments are freely defined by the performer through the MAX program.” (Schwartz, 364) Another innovator in the area of MIDI control is Tod Machover. Machover first came to prominence as one of the leading IRCAM research directors of the late 1970s. The composer developed the “hyperinstrument” concept utilizing Macintosh computers and a variety of “data gloves”. These devices were worn on the hand of the conductor and the wrist of the performer(s) and could control synthesizers in a variety of ways. Machover’s work Begin Again… (1991), was written for cellist Yo-Yo Ma (wearing the wrist device) and an array of electronic gear. As the cellist performs his portion of the piece the entire systems reacts, transforming his movements into a full orchestral accompaniment. Rounding out the lot of recent composers is the inimitable Pierre Boulez. Boulez is one of the few electronic musicians still attempting to combine musicians with larger computer systems. His work Repons was realized at IRCAM using their 4x synthesizer, a large computer, and Boulez’s Ensemble InterContemporain, “known for its astonishing virtuosity and precision under his direction.” (Schwartz, 365) During the performance of this particular piece the ensemble plays a variety of instruments whose sounds are processed through the computer. The computer then responds to the sounds by putting them through various transformations and playing them back.

All of the works mentioned above are a testament to the advances of music technology during this century. Composing used to mean sitting at a piano with pencil and manuscript and working for days only to find that, once the orchestra got together to perform the piece, it wasn’t exactly what was expected. Computer music changed this forever. Although none of the advances in music technology came quickly, come they did. “Composing computer music used to mean laboring for months on a mainframe to produce a seemingly random assemblage of bleeps and bloops that would be taped and replayed in performance. Now computers jam.” (Neuwirth, 80) Even the acoustic music purist cannot deny the ease with which compositions can be realized on the latest equipment. “The lure of computer technology has been its potential to analyze instrumental and vocal sounds and to recreate them with complete dictatorial control over the outcome and without the vagaries or expense of live performance.” (Schwartz, 366) As for the future, one thing is certain: from the very beginnings of computer music, every stage of development has seemed revolutionary until rendered obsolete. The same will one day happen with today’s technology, as has already happened with yesterday’s. Of course, better technology never guarantees better music, and often seems to the outsider to yield just the opposite. But arguments from the fringe such as these cannot stop the vision of the believers. While the validity of the electronic medium may always be denounced, the advantages are becoming more and more clear every day.

References

Hansen, Peter S. 1969. An Introduction to Twentieth Century Music. Allyn and Bacon.

Johnstone, Bob. 1994. “Wave of the Future.” Wired Magazine 2(3).

Manning, Peter. 1985. Electronic and Computer Music. Clarendon Press.

Morgan, Robert P. 1991. Twentieth-century Music. W. W. Norton.

Neuwirth, Robert. 1993. “Binary Beat.” Wired Magazine 1(5).

Schwartz, Elliot and Godfrey, Daniel. 1993. Music Since 1945: Issues, Ideas, and Literature. Wadsworth.