Granular Synthesis - "Rain"

How it works:
This sound uses the Parabolic Envelope which generates a very short arc.  When the envelope is triggered, it latches a random value for a sine oscillator using a LatchUnit.  The sine wave is multiplied by the parabolic envelope to generate a very short burst of a sinewave similar to a wavelet.  This example instantiates 8 grain circuits.  The sound on the left channel is the original grains.  The sound on the right channel is the output of a MultiTapDelay which is used to make it sound like there are more grains playing at once. Another granular synthesis technique is to multiply the envelope by a sampled sound or a complex wavetable.

• Probability - controls the likelyhood of triggering a parabolic envelope on any given sample.  Triggers are generated by a PoissonTrigger circuit that outputs a trigger whenever a white noise source exceeds a threshold determined by "Probability".
• Frequency - determines the center frequency of the sine wave oscillators.
• Spread - determines the maximum random deviation of the sine wave frequency.
• GrainSpeed - determines how quickly the ParabolicEnvelope moves from zero to maximum amplitude then back to zero.  If a ParabolicEnvelope were retriggered continuously then it would generate this many arcs per second.
• Feedback - determines how much of the delayed sound is mixed back into the delay line. This determines how long it takes for the sound to decay.