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Shepard Tone without plugin
Posted: Wed Mar 25, 2015 2:29 am
by in3D
I know there's already another topic on this but I didn't want to bump it. Is there a way I can make Shepard Tones in Audacity without being limited to that Nyquist plugin? I tried to do it using Generate Sine, Time/Pitch stretch, Fade in/out and repeat. It hasn't worked, but I was probably doing something wrong.
Re: Shepard Tone without plugin
Posted: Wed Mar 25, 2015 5:00 am
by steve
Yes it's possible, but quite tricky.
You can use the "Chirp" generator to create the sweeping tones (
http://manual.audacityteam.org/o/man/ge ... html#chirp), then use either the envelope tool (
http://manual.audacityteam.org/o/man/envelope_tool.html) or the Adjustable Fade effect (
http://manual.audacityteam.org/o/man/ad ... _fade.html) to apply the necessary amplitude changes.
Re: Shepard Tone without plugin
Posted: Wed Mar 25, 2015 3:01 pm
by Trebor
Re: Shepard Tone without plugin
Posted: Thu Mar 26, 2015 1:50 am
by in3D
Yes but I want to experiment!
I must be doing something wrong then. Used the chirp generator to make two tracks: one starting at 880 hz and 0 db fading to 440 hz and 1 db, and the other starting at 440 hz and 1 db and fading to 220 hz and 0 db. I mixed the two tracks and then repeated it once but it didn't work.
Re: Shepard Tone without plugin
Posted: Thu Mar 26, 2015 5:32 am
by steve
The simplest way is to make one track for each octave interval, and generate logarithmic chirps with a range in octaves equal to the number of tracks.
In this example I have 4 tracks, and each track sweeps from 110 Hz to 1760 Hz.
Logarithmic frequency sweeps are required to keep the tones in tune with each other (they all remain an octave apart throughout).
Each labelled region marks one octave in the bottom track:
110 - 220 Hz
220 - 440 Hz
440 - 880 Hz
880 - 1760 Hz
Note that in the final labelled section (marked "Loop this part"), all 4 octaves are present.

- tracks003.png (14.87 KiB) Viewed 1996 times
Here is a compressed copy of the project for you to examine.
Re: Shepard Tone without plugin
Posted: Thu Mar 26, 2015 5:30 pm
by in3D
That works! I tried to produce the same effect without having to trim clips but couldn't. Why is that?
Re: Shepard Tone without plugin
Posted: Thu Mar 26, 2015 7:38 pm
by steve
in3D wrote:That works! I tried to produce the same effect without having to trim clips but couldn't. Why is that?
I'd guess that it is because you're not doing something right
If you describe, step by step, exactly what you are doing (in sufficient detail so that we can reproduce it exactly), then we may be able to see what you are doing wrong.
Re: Shepard Tone without plugin
Posted: Fri Mar 27, 2015 2:50 am
by in3D
OK!
1. Generate logarithmic, sine chirp from 0 db 1760 hz to 0.25 db 880 hz in 10 seconds.
2. Generate an identical chirp from 0.25 db 880 hz to 0.5 db 440 hz.
3. 0.5 db 440 hz to 0.25 db 220 hz.
4. 0.25 db 220 hz to 0 db 110 hz.
5. Mix and render.
6. Apply repeat effect 1 time.
7. Click that line in between the two clips to make it disappear.
Re: Shepard Tone without plugin
Posted: Fri Mar 27, 2015 5:35 pm
by steve
That seems to work reasonably well for me, but to avoid getting a click at the join you may need to trim a little from the end of tracks so that all the tracks end on rising zero crossing points:

- Trim to selection
- tracks004.png (19.16 KiB) Viewed 1947 times
Re: Shepard Tone without plugin
Posted: Mon Apr 06, 2015 4:20 pm
by in3D
Ah yes thank you!