THE RAIN - Granular Texture Synthesizer

Yi Wu, Yongliang He

Spring 2018

Introduction

THE RAIN is a granular texture synthesizer VST plugin. It is our take on traditional granular synthesizer with a little twist. The randomization feature allow it to take a simple waterdrop sample and transform it into rich, rain like amorphous textures. The project is done with C++ and JUCE.

Video Demo

History of Granular Synthesis

I think it will be interesting to talk a little bit about the history of granular synthesis. Here is a research I did with Ning Yang, Aziz Ege Gonul on Dr. Curtis Roads and his Granular Synthesis on MUSI 6003 Music Technology: History and Repertoire, a class I enjoy a lot. We also tried to recreate the technology, techniques, and aesthetics of Dr. Curtis Roads’ nscor in Max/MSP as part of the research.

0.  Recreation Demo

I.  INTRODUCTION

Dr. Curtis Roads, born in 1951, is a computer music pioneer and famous microsound synthesis researcher. Roads currently serves as professor of Media Arts and Technology in UC Santa Barbara. In 1958, Xenakis composed concret PH as a first demonstration of granulation after developing gabor grain based on Dennis Gabor’s work on quantitative sound analysis. This new composition technique drew Roads’ attention when he attended Xenakis’ workshop in 1972 [1]. Only three years later, Roads composed prototype, the very first computer generated music composition using the granular synthesis method. In 1980, Roads composed his famous piece, nscor. This piece proved the potential of the use of granular synthesis for music improvisation and opened research directions for microsound synthesis. After further development by Truax to endow real-time implementation to the granular synthesis, the method was used in live performances. Today, granular synthesis is very well known among electronic musicians, thanks to the wide selection of supported software.

II.  TECHNOLOGY

A.    Early Roots

Technological implementation of the first granular synthesis was made just after World War II, by the Nobel Prize winner physicist Dennis Gabor. Before implementing a technological tool for granular synthesis, he developed a mathematical theory called Gabor Matrix.  According to his theory, a Fourier analysis is limited to describing real-life events because it only covers infinite signals in the time domain. Therefore, he fused frequency and time to represent a sound event as a single Gaussian particle. In this way, he opened the doors of representing sounds as small overlapping grains, each of them lasting between 1 to 50 ms [1].

With Gabor’s innovation, electronic music studios quickly developed similar devices using this technique in the following years. In France, Pierre Schaeffer and engineer Jacques Poullin built a granular sampler called Phonogene. It was followed by a German counterpart which was built with the help of the company called Springer. Historically, this device is known as Tempophon, and it is used in the compositions of Herbert Eimert [1].

B.    Gabor Grains

Iannis Xenakis followed the step of Gabor and consolidated his theories into “Grains of sound”, or simply, Gabor Grains [1], the elementary acoustica quanta defined by Gabor.

Xenakis composed Concret PH with granular techniques as early as 1958 in GRM studios. He used samples of burning wood to granulize sounds in his piece, which resulted in a crackling sound. A year later he focused more on granular synthesis to realize his piece Analogique A-B. He used stochastic methods heavily in combination with granular synthesis to create the piece. The term “grains of sound” was coined for the first time during this piece and he was the first musician to develop a theory for sound grains to use in the compositional context [1].

   Between 1975 and 1981, Curtis Roads experimented with digital computers to generate granular synthesis. Parameters of sound grains were entered into a punch card to control the computer and then the computer recorded sounds to magnetic tape. This process was an offline synthesis, and he established a reasonably high sampling rate of around 20 kHz with a 12-bit resolution. In 1981, he managed to increase the sampling rate to 40 KHz and used a 4-channel quadraphonic system for further experimentation. He based his granular experimentation on sampled sounds of percussions and saxophones [2].

C.    Technical Background and Realization of nscor

The core of granular synthesis consists of two elements: spectral content and envelope shape. Spectral content can be as simple as a sine wave or it can be sampled sounds. Spectral content can be accessed by time-stretching the sampled sounds and then individual grains which form the sound can be used to create granular synthesis. The envelope part of the grains is related to the amplitude and time domain of the signals. They cover the start and end of the grain window and amplitude value during the time window [1].

   Before Roads, the realization of granular synthesis (spectral content sampling, envelope shaping and organization of grains) were all manually done on tape. It required a great deal of labor to control all the parameters for each grain. In 1975, Roads developed a compositional control program on a mainframe computer that provided a solution for high level organization of the grains. The composer was only required to define a beginning set of parameters and then the program will systematically generate the traits for each individual grain. With this program, the creation of nscor become possible [3].

nscor is realized in two distinct stages. The first stage consists of a subset of stages for synthesizing the sound material from different studios, and the second stage consists of mixing and editing the final material. The core fabric of the piece was derived from another piece called Objet, which was also composed by Curtis Roads. Objet contains samples from a Moog III analog synthesizer, a Buchla 100 Series synthesizer and computer generated sounds. These sounds were all generated at UCSD and recorded on tape. After he recorded the sound materials, all the mixing and editing were done at MIT. However, not all parts of nscor use granular synthesis. He faded in granular parts during the editing process. For example, at around 0:35, he introduced sounds from a VOSIM synthesizer, and then around the 0:41 mark, he faded in a cloud of grains in the same register as the previous part. He then used this fade-in and fade-out process in the following parts to introduce different granular clouds to make a transition between the sections of the piece.

III.  AESTHETICS

A.    Expansion of the Temporal Field

The main aesthetic of the granular synthesis is composition starts from a micro-timescale. The multiplicity of time scales in compositions have been acknowledged by composers for a long time. But the expansion of the temporal field to micro-timescales did not appear until the 1930s. In 1937, John Cage envisioned a future where the composer will face the entire field of time, and the fraction of a second will be the basic unit in the measurement of time [4]. With the availability of electronic devices such as reel-to-reel tapes and wave generators in the 1950s, composers could explore the territories of micro-time. Karlheinz Stockhausen and Iannis Xenakis were among the first to explore the temporal limits of composition with tape splicing techniques. In Xenakis’s 1959 composition Analogique A-B, we can identify the micro-time aesthetics. Analogique A-B is one of the first granular synthesis composition [5]. The piece was created with the idea that all sound is conceived as an assemblage of many elementary sounds adequately disposed in time so that we can synthesize sound in a similar manner – create sounds based on grains of micro-time sampled grains [6].  However, because of the technical limits of time, their micro-time composition aesthetics, such as dense granular clouds texture, could not be fully realized until the dawn of computer synthesis.

B.    Multiscale Approach to Composition

What differs Roads’ microsound granular synthesis aesthesis from early microsound pieces is the multiscale approach to composition. Roads states that operation on one timescale could generate a structure which might perceived on another timescale [1].  In the context of granular synthesis, one can work on the micro timescale to generate high-level musical structure. Xenakis predicted this approach in 1960, stating that each grain in the granular cluster represents not only a pure frequency, but an already present structure of elementary grains [5]. Roads took this idea and realized it in nscor: a gradual change in particle duration results in timbre variations on the overall texture of the higher timescale sound. The piece starts with several sound objects and by manipulating single grains, Roads can achieve a variety of textures in the sound. With the multi-scale approach, the high-level texture of the sound could be manipulated not only by the organization of the grains on a larger scale, but also by changing the waveform, window, and duration of the grain itself at a micro-level [1][7]. This approach combines top-down and bottom-up composition strategies, allowing the composers to float freely across all timescales to maximize their creativity.

C.    Opacity and Transparency

Roads also expands the mesostructured aesthetics of granular synthesis by introducing the idea of opacity and transparency. The particle density is used to describe numbers of grains in units of time. If the density of micro-sonic events are sufficient, the temporal dimension appears to cohere, and one will perceive it as continuous clouds of texture. This texture is described as opaque sound and tends to block out other sounds that share its frequency range [1]. However, by reducing the density, one can create a transparent cloud so that other sounds can hear through it. The aesthetics of controlling texture by particle density to organized layers of sound can be clearly heard in nscor, where sometimes the granular cloud is not too dense for the other layer of sound to come above it.

IV.  IMPACT

A.    Impact on Technology

Curtis Roads granular synthesis method involves using general-purpose computer music systems for complicated calculations with a non-real-time approach. Despite Road’s creation of nscor in 1980, the bottom-line of the method prevents other musicians from accessing both the technique and the resulting sounds. Nevertheless, there are a few musicians and researchers who are inspired by Road’s granular synthesis method. They became his successors in developing a better approach and extending the method’s publicity. One of the essential works is credit to Barry Truax with his study of a real-time implementation of granular synthesis in 1980s. [8]. As described by Truax, the two major problems that existed in Road’s granular synthesis methods are large data generation and control of variable design. He used a DMX-1000 digital signal processor by Wallraff in 1979 to implement real-time granular synthesis with data generation. Four control variables are designed for the users to determine the calculation of grain parameters: center frequency and frequency range, offset number of samples from the start and offset range, average grain duration and duration range, and the delay time between grains. A few real-time control modes were also added to improve the user interface during synthesis. With the developed approach, Truax composed Riverrun (1986), the first real-time granular synthesis realized piece. After the successful approach of the real-time implementation, Truax merged physical modeling (Smith, 1992; Välimäki & Takala, 1996) and presented a diversified granular synthesis technique to create ecological sounds with sampled sound grains and meso-time control functions [9].

B.    Impact on Aesthetics

From Roads to Truax, the granular synthesis with real-time capability achieved its first stage of completion. Road’s nscor also influenced other composers with similar, but different, aesthetic approaches. Horacio Vaggione, who primarily worked on micromontage [10], an area that shares similar concepts to granular synthesis, composed Schall in 1994 with a new direction in using graphical sound editors. Paul Lansky is another micromontage composer, and under the influences of nscor, also created a few granular synthesis pieces, such as Idle Chatter (1985) [1]. This piece shares the same aesthetics of utilizing the opacity and transparency in the composition as Roads did in nscor. One can hear a dense granular cloud “evaporate” into more a transparent texture fade into the ambient background so that the vocal layer can be introduced into the front stage.

C.    Impact on Future

Since the SynthO-Matic by James McCartney in 1990s, the granular synthesis method has been used in numerous computer programs. Truax used Csound to implement synthesis techniques with his research of environmental sounds [9]. Xenakis built UPIC (Unite Polyagogique Informatique de CEMAMu) in 1977, and provided it to Brigitte Robindore in 1995 to compose Comme Etranger et voyageurs sur la terre [1]. Multiple granular synthesis programs were developed for functional use. Mac-POD by Damian Keller and Chris Rolfe [11], AL & ERWIN by Rajmil Fischman [12], Granulab by Rasmus Ekman and Granulator by Nicolas Fourne [13] are a few of the representative programs. Some programing languages such as Supercollider, Max/MSP are also compatible with granular synthesis.

V.  CONCLUSION

From Gabor to Xenakis, and Roads to Truax, granular synthesis methods have been widely used by hundreds of composers today. Both the increase of computing power and optimization in the software implementation have made the live performance of granular synthesis sound like they are pre-recorded. Composers no long have to depend on huge computing systems and pre-calculate all the values to generate music pieces like Roads did in prototype and nscor. Neither do they have to obtain professional knowledge on microsound synthesis to compose or perform. Sufficient software programs, plugins and patches ensure the musicians can utilize granular synthesis methods with minimal coding capabilities and bring computer improvised granular synthesis to the public.

REFERENCE

[1]        C. Roads, Microsound. The MIT Press, 2001.

[2]        C. Roads, "Introduction to Granular Synthesis", Computer Music Journal, vol. 12, no. 2, p. 11, 1988.

[3]        C. Roads, Foundations of computer music. Cambridge, MA: MIT Press, 1987.

[4]        Cage, J.  THE FUTURE OF MUSIC: CREDO. Music Journal, 20(1), 44, 1962

[5]        C. Roads, “From Grains to Forms,” in Proceedings of International Symposium, Saint-Denis, France, 2012.

[6]        C. Roads, The Computer Music Tutorial. The MIT Press, 1996.

[7]        C. Roads, Composing electronic music a new aesthetic. New York: Oxford University Press, 2015.

[8]        B. Truax, “Real-Time Granular Synthesis with a Digital Signal Processor,” Comput. Music J., vol. 12, no. 2, pp. 14–26, 1988.

[9]        D. Keller and B. Truax, “Ecologically-based Granular Synthesis,” in ICMC, 1998.

[10]       Roads, Curtis. “The Art of Articulation: The Electroacoustic Music of Horacio Vaggione.” Contemporary Music Review, vol. 24, no. 4-5, 2005, pp. 295–309.

[11]       D. Keller and C. Rolfe, “The Corner Effect,” Proc. XIIth Colloq. Music. Informatics, Gorizia, Italy, 1998.

[12]       R. Fischman, “Clouds, Pyramids, and Diamonds: Applying Schrödingers Equation to Granular Synthesis and Compositional Structure,” Computer Music Journal, vol. 27, no. 2, pp. 47–69, 2003.

[13]       T. T. Opie, “Creation of a real-time granular synthesis instrument for live performance,” dissertation, 2003.