Synchronous granular synthesis produces ordered streams while asynchronous synthesis produces stochastic clouds

Within granular synthesis, the synchronous/asynchronous distinction is compositionally fundamental. Synchronous granular synthesis (SGS) emits one or more streams of grains that follow each other at regular intervals — an ordered, metrical output. Asynchronous granular synthesis (AGS) abandons sequential streams and instead scatters grains irregularly over a duration within regions of the time-frequency plane, controlled by a stochastic algorithm; these regions are ‘clouds,’ the units with which the composer works. The discriminator is order versus scatter: in SGS the ear hears a regular stream or fused tone, in AGS a cloud whose density reads as transparency-or-opacity rather than rhythm. Choosing SGS versus AGS is the first structural decision in granular synthesis.

Examples

SGS: a regular grain stream heard as a pulse or, at high density, a fused tone. AGS: a cloud where grain timing is stochastic within a time-frequency region and density sets how transparent or opaque the texture sounds.

Assessment

Describe the difference between synchronous and asynchronous granular synthesis, and say what a listener hears from each (stream/tone versus cloud).