This document discusses various topics related to generative music and sound, including: - References to early works exploring mathematical and algorithmic approaches to music. - Descriptions of projects that generate music from chaotic systems like the Lorenz attractor. - Details of using Raspberry Pi and cheap DACs to generate analog signals from chaotic attractors to drive analog synthesizers. - Plans to control two Duffing oscillators to modulate parameters of other oscillators and trigger drum sounds on synthesizers.

1. https://www.slideshare.net/gilesgreenway
NEVER MIND
THE MOLLUSCS
(MIS)ADVENTURES IN
DR GREENWAY (@AUGEAS)

2. https://www.slideshare.net/gilesgreenway
“We have also sound-houses, where we practice and demonstrate
all sounds and their generation. We have harmonies, which you
have not, of quarter-sounds and lesser slides of sounds. Divers
instruments of music likewise to you unknown...” Francis Bacon, The
New Atlantis, 1627. https://www.gutenberg.org/ebooks/2434
Daphne Oram: https://youtu.be/NNaqvAH7R34
http://www.ubu.com/historical/oram
“Some people object to such a view of music, saying that if you
reduce music to mathematics, where does the emotion come into it?
I would say that it's never been out of it.” Douglas Adams, Dirk
Gently's Holistic Detective Agency

3. https://www.slideshare.net/gilesgreenway
““And the peculiar thing is thisAnd the peculiar thing is this
my friends:my friends:
The song we sang on thatThe song we sang on that
fateful night it didn't actuallyfateful night it didn't actually
soundsound
Anything like this song.Anything like this song.
This is just a tribute!”This is just a tribute!”
The Art of Noise
"Fight Your Own War: Power Electronics and
Noise Culture" Edited by Jennifer Wallis
https://headpress.com/

4. https://www.slideshare.net/gilesgreenway
The Great Generative Music Swindle
“Oblique Strategies
Against Humanity”
EMF 2016.
https://youtu.be/b03P4eaeUzE
“(In)discrete Music”
SHA 2017.
(headlined by mistake)
https://youtu.be/8LaoaS3PIfM

5. https://www.slideshare.net/gilesgreenway
“Picked you up on my TV screen...”
“Knittable Seashells by
Fabienne Serrière”
Strangeloop 2017.
https://youtu.be/3JwSFxpXIFE
KnitYak, Computationally Generated
Knitwear. https://knityak.com
@knityak @fbz
“Knittable Seashells by
Fabienne Serrière”
Strangeloop 2017.
https://youtu.be/3JwSFxpXIFE

6. https://www.slideshare.net/gilesgreenway
“Take me to your Lizard”
Lizard scales as automata cells: “A living mesoscopic cellular
automaton made of skin scales”
https://www.nature.com/articles/nature22031

7. https://www.slideshare.net/gilesgreenway
“I can’t tell you what I’ve found.”
May or may not come with software.
https://www.springer.com/gb/book/9783
https://www.springer.com/gb/book/9783
Legit pdf + code:
http://algorithmicbotany.org/

8. https://www.slideshare.net/gilesgreenway
“I can’t figure out your watery love.”

9. https://www.slideshare.net/gilesgreenway
“I can’t figure out your watery love.”
CASE 61 '-- Branches controlled by a hormone : Olivia Porphyria
----------
' Hormone (c) changes lifetime of the inhibitor
FOR i = ja TO js: GOSUB olddecay:
aq = s * a * a / (1! + sA * a * a) + ba
axt(1, i) = olddecaydiffA + aq / (sb + b)
axt(2, i) = olddecaydiffB + aq + bb
ahorm = ahorm + rc * a 'hormone production by a
IF i = js THEN 'averaging
CALL hormone(3, ahorm, ja, js)
rbb = rB / C '---- effective inhibitor decay rate
drb = 1! - 2! * db - rbb
END IF
NEXT i
Old code runs on FreeBASIC. Slowly being turned
into vectorized Python/Numpy.
https://github.com/augeas/NeverMindTheMolluscs

10. https://www.slideshare.net/gilesgreenway
“I can’t figure out your watery love.”
Oliva Porphyria

11. https://www.slideshare.net/gilesgreenway
Interlude: “Your Gauss is as good as mine”
For α, β create a sequence of x values.
Each slice through the map is a histogram of the x values.
Vary β on the horizontal axis.
Plot x on the vertical axis, α varies in time, scan β up and
down.

12. https://www.slideshare.net/gilesgreenway
Bifurcation diagrams as spectra
Take the inverse real discrete
Fourier transform of each
histogram. (numpy.fft.irfft)
Multiply each chunk of signal
by a window function.
Offset each chunk by
successive hops and
superimpose them.
Right channel is the left
channel played backwards.
Pan according to the centre of
the distribution.

13. https://www.slideshare.net/gilesgreenway
I think you’ll find it’s more complex than that.
d.c. d.c.Nyquist
complex
frequencies
complex
conjugate
frequencies
frequency axis
amplitudeaxis
real
imaginary
phase
angle

14. https://www.slideshare.net/gilesgreenway
I think you’ll find it’s more complex than that.
Main signal from Oliva Porphyria.
Real amplitudes come from the activator.
Complex amplitudes come from the inhibitor.
Pan the signal according spectrum’s “centre of mass”.
When the spectrum is centred, trigger another mollusc.
(Four substances in the triggered simulation, use both
channels.)

15. https://www.slideshare.net/gilesgreenway
“Merry Christmas, Mr Lorenz”
http://users.physics.harvard.edu/~horo

16. https://www.slideshare.net/gilesgreenway
Chaotic Things To Do
●
In-browser attractor sounds via the web audio api
and SVG. (http://augeas.github.io/Chaoscillator/)
●
Use Clojure to control SuperCollider via Overtone. (
http://overtone.github.io/)
●
Build a Lorenz attractor LFO as a LV2 plugin in
C/C++. (http://lv2plug.in/)
●
Build a Lorenz attractor LFO as a module for VCV
Rack in C/C++. (https://vcvrack.com/)
Give in, resort to quantizing to 128 MIDI notes (Or cheat).
●
Create chaotic attractor signals on a Raspberry Pi.
●
Audio digital to analogue converters might filter out low frequency
signals.
●
Use the GPIO pins to drive cheap-and-cheerful DACs.
●
Use the output to drive analogue synths.

17. https://www.slideshare.net/gilesgreenway
Duffing’s Oscillator

18. https://www.slideshare.net/gilesgreenway
This is what you want, this is what you get.
Want:
●
Good resolution. Multiple channels.
●
I2C > SPI.
●
Through-hole.
●
Cheap.
●
End up with 10-bit 2-channel SPI DACs.
It’s all spotty!
●
Smere out the points
with a passive RC
filter.
●
Now sufficiently
analogue.

19. https://www.slideshare.net/gilesgreenway
This is what you want, this is what you get.
●
Two Duffing attractors.
●
Frequency and modulation frequency
controlled by x and y variables of 1st
attractor.
●
Amplitude and filter cut-off frequency
controlled by 2nd
attractors.
●
Attractors switched for Moog Mother32 and
Werkstatt.
●
Crossing of x and y axes triggers low and
high toms or open and closed hats on Korg
Volca Beats.
●
α, β, and γ varied by slow sinusoids.