Help: Apple II Sound Trick

[Kermit <kermit@novadesign.com>]

When I was in college, oh so long ago in the 1978-82 period, an article
came out documenting how to make Apple II's 1bit speaker make sounds
that sounded louder and better than the 'beep'-type sound typical of so
much game music.

What I recall of the technique involved rapidly alternating frequencies
or notes or such to create a harmonic effect. It sounded like an etheral
hum.

The article documented this with asm or more likely BASIC code to do the
effect. 

Does anyone recall this article? Have the article? Have a pointer to it
on the web??

Many thanks in advance to any who can help. Copy me on any answers via
email if possible. I will check here though.

Kermit Woodall