Assignment 4: Granulation

What we’re trying to do

What to turn in

Granulation with Granulator

Granulator is an application, built in Max 6, that performs real-time granulation of sampled sound. To granulate a sound is to break it up into many tiny grains — each anywhere from a few milliseconds to about a half second in duration. Each grain is subjected to an amplitude envelope and can be independently transposed. The grains flow out of the granulator in one or more streams, one grain after another. The time between successive grains determines the grain rate, or grain speed, which has a profound impact on the sound. If the grain rate is regular, you may hear a pitch with a frequency corresponding to the time between successive grains. If the grain rate is randomly varied, this pitch disappears.

Why would anyone want to granulate sound? The applications range from time-scaling audio to making a sustained sound out of a short snippet (e.g., a choral sustain from a guitar pluck) to creating interesting noisy or pulsed repetitive textures. Play with it to discover.

Granular synthesis does the same thing, but instead of taking grains from a sound file, it synthesizes grains, using simple wavetable or FM synthesis. (We don’t have a plug-in that does this.)

One of the first composers to explore granular synthesis, Barry Truax, likes to use granulation as an audio microscope, zooming in on sound and exploring its details in slow motion.

Here are some steps to get started using Granulator.

  1. If you’re working in MC304, Granulator is already installed, inside /Applications/jgapps/. Drag its icon to your Dock.
  2. If you want to install Granulator on another Mac, download the software and un-zip it, if necessary.
  3. Launch the program by double-clicking the Granulator file. (Ignore the granpresets.xml file.)
  4. If the Mac complains about running something written by an unidentified developer, launch the program instead by right-clicking (or control-clicking) on the program icon, and choosing Open in the dialog box that appears.
  5. Press the Audio Driver button, and choose the appropriate item from the Driver pop-up menu. In 304, this should be MOTU Traveler.
  6. Press the speaker icon to turn on audio.
  7. Drag a sound file into the empty waveform rectangle.
  8. Lower the output volume fader, just in case something loud happens.
  9. Press Play to start granulating. You might need to choose the top-left square from the Presets grid.
  10. Drag in the waveform to select a portion to granulate, and fiddle with the parameters.
  11. To record the sound you’re making, first set the output format to 24-bit (either AIFF or WAV), press the Record button, choose a name and place to store the output file, and press Save. Granulator will record what you’re doing until you press the Stop button that is under the Record button.

©2010-2018, John Gibson