Murdertones!

Here is an idea, a new possible technique. This may mean that Extratone can always accelerate without slowing down or drifting into ringing/silence. Sounds impossible? Let me explain!

Here is a gif of a barber's pole. There is an optical illusion at play here, so the pattern appears to always be rising and never falling. The Shepard Tone applies exactly the same idea, but with sound!

Image result for shepard tone

As shown, aside from the highest and lowest notes (which can be faded in/out or just go unnoticed) the notes are in the same state after sliding-up as they were before. Meaning this pattern can be looped over and over again seamlessly. Always rising but never escaping the chosen range of frequencies! HERE is an example.

Extratone producers are fond of blurring the line between tempo and frequency, so I'm trying to transfer this illusion from pitch... to BPM! So these will be called... Murdertones! So far my results have been varied, maybe you can help me in this experiment? Here is a recipe for producing a simple (2 layer) Murdertone:

Recommended tools: Audacity and Extratone Girlfriend
1. Pick a base tempo, X. Make it high (1000+BPM)
2. Record a pattern, Pattern 1, going from X to 2X BPM.
3. Record Pattern 2, going from 2X to 4X BPM, but make it last the same amount of time.
Pattern 2 needs twice as many beats as Pattern 1 if you are using the Extratone Girlfriend.
So if 'total beats' is 100 for Pattern 1, make it 200 for Pattern 2.
4. Make Pattern 1 fade in from silence.
5. Make Pattern 2 fade out to silence.
6. Play the two patterns simultaneously!
7. Copy and paste the resulting sound, make it repeat as much as you like!

I expect more layers = better results. So far I have only tried this experiment with 2 layers and 4 layers. They can both blend seamlessly, but there is room for improvement. In my experience it sounds better with plenty of reverb (increase 'wet', decrease 'dry'). When I have more free-time I hope to include an Murdertone generator in the Extratone Girlfriend to make the process easier and quicker, but right now I am too busy. Please do experiment with this idea, I think it has potential!

For fun, I made a reverse-Murdertone which created a cool slowing-down effect, and I'm using it in a track which will appear on an upcoming Eater of Sheep EP. Stay tuned!

420 update:
-8 layers example HERE. Far from perfect, need to make it more gradual or something.
-7 layers example with linear change HERE. Took a little bit of maths to get the layers all the same length. Results in interference, unsurprisingly, so there's like an extra rhythm which ruins the illusion.
-Renamed from Extrashepardtones to Murdertones, as it appears 7!cHO had a very similar idea HERE.