New Media Production 2 MUMT 303 Week 6 Sven-Amin Lembke Granular - - PowerPoint PPT Presentation

Week 6

New Media Production 2

MUMT 303 Sven-Amin Lembke

Granular synthesis

Grains

• based on sound grain defined by ...
• amplitude envelope ...
• duration typically 5-50 ms
• envelope shape:
• Gaussian, Tukey, v. Hann
• triangular, trapezoidal
• decaying exponential
• grain content:
• any waveform

Granular synthesis: history

• Dennis Gabor, electrical engineer and physicist
• in 1940s developed theory that any sound can be

described by granular or quantum representation

• established term of acoustical quanta
• Gabor’s theory taken up by other persons ...
• in 1964 Wiener supported quantum view of sound
• in 1968 Moles derived first physical representation
• in 1980 Bastiaans verified theory mathematically

Granular synthesis: in music

• Iannis Xenakis, composer and architect-engineer
• first to use granular techniques in musical contexts,

using magnetic tape manipulation:

• Concret PH 1958
• Analogique A et B 1958-59
• formalized compositional theory for grains of sound:
• Formalized Music 1971

Granular synthesis: in music

“All sound, even continuous musical variation, is conceived as an assemblage of a large number

• f elementary sounds adequately disposed in
• time. In the attack, body, and decline of a

complex sound, thousands of pure sounds appear in a more or less short interval of time Δt.”

• Xenakis

Granular synthesis: in music

• Curtis Roads, composer and granular pioneer
• created first computer-based synthesis

implementation:

• at UCSD in 1974 and MIT in 1981
• implemented as front-end processor to MUSIC V
• contributed documentation of methods:
• articles in Computer Music Journal
• book Microsound 2001

Granular synthesis: in music

• Barry Truax, composer
• developed first real-time synthesis implementation in

1986:

• using DMX-100 digital signal processor
• allowed up to 20 simultaneous voices (polyphony)
• approach seen as a form of real-time composition:
• Riverrun 1986

Granular synthesis: in music

"The fundamental paradox of granular synthesis--- that the enormously rich and powerful textures it produces result from its being based on the most 'trivial' grains of sound---suggested a metaphoric relation to the river whose power is based on the accumulation of countless 'powerless' droplets of water."

• Truax

Granular synthesis: in music

• Jones and Parks experimented with grains containing

recorded samples:

• granulation seen as decomposition of sampled

sounds into grain sequences

• experimented with time-frequency manipulations
• Risset and Wessel in 1982 worked with granular

methods in a analysis/synthesis system

• related developments in other fields:
• wavelet-transform, developed at Center for

Theoretical Physics in Marseille, France

• particle-synthesis, developed by Reeves in 1983

Granular synthesis: methods

• Simple definition of granular techniques difficult:
• no standard implementation
• no relationship to classical signal processing

synthesis techniques

• Two main groups for synthesis approaches:
• synchronous granular synthesis
• asynchronous granular synthesis

Synchronous granular synthesis

• Synchronous synthesis involves repetition of grains at

a constant rate.

• Inherently corresponds to amplitude-modulation

(AM) ...

• modulator: grain envelope at repetition rate
• carrier: grain content (waveform inside grain)
• generates sidebands in spectrum
• Applications in speech synthesis:
• FOF (fonction d’onde formantique)
• VOSIM, voice synthesizer

Synchronous granular synthesis

• AM involved with synchronous synthesis ...
• determined by grain length, repetition rate and

envelope shape

Asynchronous granular synthesis

• Asynchronous synthesis involves random distribution
• f grain timing.
• Instead of controlling parameters ‘grain-to-grain’,

higher-level control of parameters often employed

Asynchronous granular synthesis

• There is a multitude of approaches for higher-level

controls of grain parameters:

• Wishart: texture manipulation
• GRM: brassage
• Roads: events
• Xenakis: screens
• Truax: tendency masks

Asynchronous granular synthesis

• Still, there are commonalities across asynchronous

synthesis approaches ...

• in generating so-called clouds

Asynchronous granular synthesis

• Still, there are commonalities across asynchronous

synthesis approaches ...

• in generating so-called clouds

Truax, 1986: Riverrun

Asynchronous granular synthesis

• Commonalities across asynchronous synthesis

approaches ...

• employing common controls parameters ...
• grain envelope
• grain content
• pitch and amplitude
• grain density (delay and length)
• spatialization

Granular synthesis and perception

• Truax discusses psychoacoustical variables involved

with granular synthesis ...

• pitch to noise continuum
• temporal spacing between grains
• <50 ms continuous texture
• >50 ms separate events
• (isolated) sound grains ...
• preclude pitch percept if <13 ms
• only exhibit emergent timbre for >40-50 ms