In the June 1997 issue of Keyboard magazine is an article, "Granular
Synthesis", by Curtis Roads, associate editor of the prestigious Computer
Music Journal, who writes:

 "One of the important new methods [of sound synthesis] is _granular
  synthesis_.  This approach builds up acoustic events by streaming or
  scattering acoustic particles in time and space.  Each particle or
  'grain' lasts only an instant, typically 1 to 10 milliseconds.

 "As the Nobel-prize-winning physicist Dennis Gabor showed in 1946, any
  sound can be analyzed and reconstructed by means of acoustical quanta,
  or grains."

The illustration says, "Anatomy of a grain - a brief audio signal with an
amplitude envelope, typically bell-shaped.  The waveform inside the grain
can vary from grain to grain, which gives the granular representation
unusual flexibility.  Other parameters of the grain include the frequency
of its waveform, its amplitude coefficient, and its spatial location."

The article invites the reader to download a freeware demonstration from
their web site (http://keyboardmag.com) but I wasn't successful.  A
search on Alta Vista yielded several interesting articles, including
"The development of GiST, a Granular Synthesis Toolkit Based on an
Extension of the FOF Generator", by Gerhard Eckel and Manuel Rocha
Iturbide, of IRCAM, Paris, France, and Barbara Becker, GMD, St. Augustin,
Germany, at

  http://viswiz.gmd.de/~eckel/publications/eckel95c/eckel95c.html

Roads concludes his article in Keyboard:

 "The question of how to compose with microsonic materials remain.
  A clue can be found in a recent composition by Horacio Vaggione,
  professor of composition at the University of Paris VIII.  His 1995
  tape composition "Schall" consists of tens of thousands of sound
  particles derived from sampled piano notes.  What makes this
  composition unique is its brilliant use of the notion of switching
  between different time scales: from the microscopic up to the
  note-object level and down again into the microscopic.

 "Schall" is not merely an academic demonstration, however: it justifies
  innovative means on the plane of musical listening.  Of course not all
  musicians will follow a systematic approach to granular synthesis, nor
  should they.  It is perhaps more appropriate to think of granular
  synthesis as just an additional instrument in the orchestra of the
  electronic musician, that is to say, in the orchestra of the 21st
  Century."

Robbie Rhodes