Interestingly, the effect of the overlapping grains can be simply explained as a comb-filter delay. If one assumes a fixed grain envelope, an asynchronous grain six milliseconds later than the original is simply a six- millisecond delay mixed in with the original signal. Resynthesis parameters are thus directly linked to a finite time length. Rate of change is scaled according to the length of this event. These settings define ranges of possible values for the local parameters.
Local parameters determine the overall behavior of the high-level event.
If grains with fixed duration are evenly scattered along a predefined time span, we get an invariant average density. If synthesis parameters vary independently, we will spend several trials until we find the right amount of grains and the right rate of change in distribution. On the other hand, by using grain overlap as the only control variable and letting the quantity of grains and the overall duration change accordingly, we will be dealing directly with the relevant perceptual parameters. In this example, the only high-level variable that needs to be defined is the rate of change in grain overlap. The conclusion We have investigated several issues involved in the implementation of a real-time granular synthesis application.