Social top



Introductory texts about composers and their works by students and emerging authors

Granular Synthesis and Barry Truax’s Riverrun

The advancement and evolution of electroacoustic music has always had strong ties to the technology that the music was realized through. Many technological leaps and ideas since the discovery of electricity have found applications in the development of music. In response, many electroacoustic composers have integrated their knowledge and skill of electronics and computers into their work with music. Barry Truax is one of these multi-faceted composers who has made significant advancements in technology, composition, and acoustic ecology. His work is widely published and has influenced people around the world.

Truax has contributed to the development of many different types of electroacoustic compositions, and is perhaps best known for the development of granular synthesis, prominently featured in his 1986 piece Riverrun. Drawing its name from the first word of James Joyce’s Finnegans Wake, Riverrun is a texturally rich piece in which Truax takes thousands of tiny “droplets” of sound and combines them to form a dense “river.” The technique used in this piece, granular synthesis, involves taking tiny, sometimes less than fifty milliseconds. grains or “drops” of sound and playing them simultaneously. With the aid of a computer, each “grain” is changed in pitch, timing, or duration to create the effect of a rich and flowing texture.

The idea of granular synthesis and the techniques used to compose it stem back deep into the history of electronic music. Iannis Xenakis was among of the first to explore the idea of granular synthesis. In his book Formalized Music, Xenakis describes all sound as “an integration of grains, of elementary sonic particles, of sonic quanta” (Xenakis 1971, xiii). Karlheinz Stockhausen also explored a similar idea in his 1960 masterpiece, Kontakte, in which he explored the unity of sound on a fundamental level, the relationships between pitch, rhythm, timbre, tone etc. In a defining moment in the piece, “Struktur X,” Stockhausen slows down a single, pitched tone until it eventually becomes a series of slow clicks, suggesting the relationship between pitch and rhythm. In the same instance, Stockhausen is also suggesting that at its smallest level, all tone is rhythm, just a collection of sped up “clicks.”

Another pioneering idea behind the development of granular synthesis is additive synthesis. Additive synthesis is the technique of creating sonic complexity by addition of waveforms. Depending on one’s resources or technology, one can create dense and rich sounds from simple sound sources. While granular synthesis may have existed in a basic form before the advent of computer technology, it wasn’t able to come to its full realization until later.

Before developing computer music, Barry Truax had started composing works for acoustic music as early as 1969. Born in Chatham, Ontario in 1947, Truax attended Queen’s University in 1969 before being introduced to electronic composition at the Institute of Sonology of Utrecht University. Studying under renown composers like Gottfried M. Koenig and Otto Laske, Truax experimented with FM synthesis in his early electronic compositions. After Utrecht, he left Europe to work back in Canada at Simon Fraser University where he developed further his work with computer music. Truax was also at the forefront of computer technology, one of his first major contributions being the PODX system. PODX allowed real-time manipulation of computer-generated sound. Indeed, real-time granular synthesis, as featured in Riverrun, became Truax’s signature technique.

This piece is therefore “computer music” because real-time granular synthesis could only be accomplished by a computer. Truax takes small parts from both sine waveforms and sound samples and breaks them into tiny grains of sound and then manipulates these grains by pitch, duration, timing, etc. With the aid of a computer, up to thousands of these grains are played simultaneously to create lush soundscapes. Using a computer, Truax is then able to change these parameters in real-time to enhance and transform the composition.

The development of granular synthesis is also significant to other aspects of electroacoustics, most prominently time stretching. The importance of Riverrun and of the development of real-time granular synthesis, was acknowledged by the international electroacoustics community by way of the prestigious Magisterium award at the Bourges International Competition of Electroacoustic Music which he received in 1991. Composed in 1986, Riverrun explores the effects of real-time manipulation of both synchronous and asynchronous granular synthesis techniques. At its most basic form, Riverrun is composed of thousands of grains taken from sine waveforms. Conceptually, Truax suggests that each of these small grains is a tiny droplet of water. It takes millions of these tiny droplets to form a body of water like a river. As the number of these droplets grows, so does the river until it seems to form into a single, homogenous stream of sound. At its smallest level, the grains of sound are so small that they are identical whether played backwards or forwards. The whole texture could be played backwards and still remain identical to its original form.

Originally in four channels, Riverrun was composed through a host of computer programs and devices including a DMX-1000 DSP,among others. On a small scale, the samples generated by the computer can then be altered in envelope in order to reduce clicks or unwanted parts of a sound. Truax himself suggests that a “short, linear attack and decay” works best for sampled sounds. At first, the piece begins with streams of short droplets, growing in density and speed. It’s amazing to hear how such small sonic quanta can quickly meld together to create a flow that doesn’t sound hard or cut-up. The sound sources used all have a sine wave characteristic, however Truax succeeds in creating this feeling of a “river” of sound. Truax also uses drawn-out, airy sounds that have a character to them that’s not unlike a woodwind instrument or even a voice at times. These drone-like sounds are mainly used to bridge together the different sections of the piece.

Overall the piece is composed of five major sections. Each section is characterized by the buildup of these streams of granulated, water-like textures and how they change. The first section starts with small streams of droplet forming which build up for the first five minutes of the piece into an eventual dense, homogenous stream. This buildup ends as the stream turns back into a single droplet of sound. The droplets eventually become increasingly denser until they form once again a dense stream, but this time Truax is constantly morphing and changing the texture in various ways. Sections three and four of the piece(starting at 8:45 and 11:00, respectively) continue in this manner. In the ending of the third section, instead of choosing to have the sound fade out until another texture comes in, he gradually decreases the amount of mid-range frequencies until what is left sounds like a drawn out, choir “ahh” sound that meets with the next texture. The next sections buildup involves the stream moving almost into a single dense stream that feels like it has its own overall tone and pitch until finally it is met with a contrasting low-range drone.

The fifth and last section, which begins 14 minutes into the piece, combines multiple layers of granulated “rivers” played simultaneously each one having its own degree of density.The lower layer, which contains dense low-range sounds, changes little throughout the section. The mid- and high-range frequency parts start as almost two distinguishable layers but form in and out of each other in the last section. This is visible on the spectrograph as two streams made up of four vertical rows each that constantly move in and out from one another. At the very end of the piece the low frequency layer is eventually taken away, leaving dense the high-frequency streams as the only sound source and eventually fades out.

The contributions of Barry Truax and others greatly helped such techniques as those used in Riverrun available to the general public. Granular synthesis has become a cornerstone in compositions by contemporary composers around the world. Works by Christian Fennesz and Tim Hecker transform something as simple as an electric guitar into a lush, immersive soundscape that seems to put time on hold. Timestretching is a tool included in every major DAW and is finding use in all forms of composition and production work. Riverrun, now over twenty years old, still impresses composers young and old and is still being presented all over the world. Like each individual grain used to build into Truax’s monstrous “river,” this work, his others, and the bit-by-bit contributions from composers everywhere has helped transform the electroacoustic community into what it is today.


Ford, Clifford, Richard Green and Evan Ware. “Barry Truax.” Encyclopedia of Music in Canada. The Canadian Encyclopedia. Last accessed 4 April 2008.

Truax, Barry. “Granulation of Sampled Sound.” Composer’s website. Last accessed 7 April 2008.

_____. “Granular Synthesis.” Composer’s website. Last accessed 5 April 2008.

_____. Riverrun. Composer’s website. Last accessed 4 April 2008.

Xenakis, Iannis. Formalized Music: Thought and Mathematics in Composition (Harmonologia Series No.6). Hillsdale, NY: Pendragon Press, 2001.

Social bottom