🚀 go-pugleaf

RetroBBS NetNews Server

Inspired by RockSolid Light RIP Retro Guy

Article View: comp.sys.mac
Article #22526

Re: Sonic Holography - Shepherd's Tones

#22526
From: Carl Tollander
Date: Fri, 04 Dec 1987 20:33
27 lines
1810 bytes
  >Plus, there is an audio illusion I've been looking for, for quite
  >a while now. Basically it is an ever increasing tone. 

It (they) are called Shepherd's Tones.  I forget where I saw this first
or why they're called that.  Basically, you take several oscillators (voices),
let's say, four.  Number them 1-4.  Each voice can vary equally in
frequency and amplitude.

Start with all voices at low frequency, low amplitude.
Slowly raise the frequency and amplitude of the first voice.
At about its mid-range, slowly decrease the amplitude of the first voice.
At the same time, start slowly raising the frequency and amplitude
of the second voice.  At about the mid-range, slowly decrease the amplitude.
Repeat for however many voices you have.  When a voice becomes sub-audible,
change the frequency back to low again and begin to raise the frequency
and amplitude.  The first voice should go sub-audible at the same
time as the fourth is starting to become audible.  Wrap the process from 
the last voice to the first.

The effect is something like a circular bucket brigade, with the "bucket"
being the perceived rise in tone.  The method works for descending tones as
well.

----------------------------------------------------------------------------
Carl Tollander
ARPANet: carl@ads.com
Technical Details
Message-ID: <8712042033.AA02881@distance.ads.arpa>
Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!think!ames!ucbcad!zodiac!DISTANCE!carl

Show Full Headers
Complete Article Headers
Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!think!ames!ucbcad!zodiac!DISTANCE!carl
From: carl@DISTANCE (Carl Tollander)
Newsgroups: comp.sys.mac
Subject: Re: Sonic Holography - Shepherd's Tones
Message-ID: <8712042033.AA02881@distance.ads.arpa>
Date: Fri, 4-Dec-87 15:33:44 EST
Article-I.D.: distance.8712042033.AA02881
Posted: Fri Dec  4 15:33:44 1987
Date-Received: Wed, 9-Dec-87 05:53:27 EST
Sender: daemon@zodiac.UUCP
Lines: 27