Bill Kibler's observation  about my story of adding white noise to the
tone generator output allows me to add a "postscript".  I recalled
that the gentleman installing the organ explained that the airflow in
real pipes generated a certain amount of white noise and that by
injecting white noise into the tone generator output the resultant
signal more closely approximated/imitated the sound of a true pipe.

Regards
Harvey

"I live with fear, death, and evil...  but sometimes I turn it off
and use a Mac. "  Author Unknown