Artificial Neurons and Nonlinear Mixing

Talking through the concept of an artificial neuron, the fundamental component of artificial intelligence and machine learning, from an audio perspective.

I’ve made a few videos recently with “artificial neurons” including in Pure Data and in Eurorack, and, in this video, I discuss the ideas here in more detail, specifically how an artificial neuron is just a nonlinear mixer.

An artificial neuron takes in multiple inputs, weights them, and then transforms the sum of them using an “activation function”, which is just a nonlinear transformation (of some variety).

Of course just making a single neuron does not mean you’ve made an artificial intelligence or a program capable of “deep learning”, but understanding these fundamental building blocks can be a great first step in demystifying the growing number of machine learning programs in the 21st Century.

More music and sound design with artificial neurons:

Pure Data Clamping VCA with [clip~]

Creating an ambient music machine in Pure Data Vanilla with a “clamping VCA” that adds subtle distortion, imitating the envelopes in Roland TR-808.

I made a clamping VCA in Reaktor a few weeks back, and now here’s another example in Pd. Normally, amplitude envelopes in synths are a control envelope on the amplitude of the signal. When we use a “clamping VCA”, though, instead of controlling the amplitude of the waveform, we clip it at the desired maximum envelope. This means, when the VCA is all the way up, it sounds the same, but during the attack and release, we’ll get the addition of subtle (or perhaps not-so-subtle) distortion to our waveform.

I use [clip~] in Pd to achieve this effect, stealing the idea from Noise Engineering’s “Sinclastic Empulatrix” module, which, in turn, stole the idea from from the Roland TR-808 drum machine’s cymbal envelopes.

More Pure Data Tutorials:

Clamping VCA in Reaktor 6 Primary

Building a “clamping VCA” in Reaktor for subtle distortion, imitating the envelopes in Roland TR-808.

Normally, an amplitude envelope for your synths are just that: a control envelope on the amplitude of the signal. When we use a “clamping VCA”, though, instead of controlling the amplitude of the waveform, we clip it at the desired maximum envelope. This means, when the VCA is all the way up, it sounds the same, but during the attack and release, we’ll get the addition of subtle (or perhaps not-so-subtle) distortion to our waveform.

I use the “Mod. Clipper” in Reaktor 6 to achieve this effect, stealing the idea from Noise Engineering’s “Sinclastic Empulatrix” module, which, in turn, stole the idea from from the Roland TR-808 drum machine’s cymbal envelopes.

0:00 The “Mod. Clipper”
0:33 Clamping VCA
1:25 Simple Sine Oscillator
2:03 Mod-Clipping the Sine Wave
3:51 Standard VCA for comparison
4:58 Pulse Wave
5:41 Sawtooth Wave
6:34 Adding a Filter
7:35 Next Steps

More Reaktor 6 Intermediate Tutorials:

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Thinking Beyond the ADSR, Other Envelope Generators in Reaktor 6 Primary

Adding envelopes to our synthesizer that aren‘t an ADSR.

ADSRs might be the envelope generators that we encounter most often, but they’re not the only way to shape our sound. There are a number of other musical ways to craft change in our synthesizer over time with these non-periodic TVCs.

Let’s check out what other options there are in Reaktor 6 primary.

More Reaktor 6 Beginner Tutorials here:

Pure Data Artificial Neural Network Patch from Scratch

Coding (well, “patching”) an artificial neural network in Pure Data Vanilla to create some generative ambient filter pings.

From zero to neural network in about ten minutes!

In audio terms, an artificial neuron is just a nonlinear mixer, and, to create a network of these neurons, all we need to do is run them into each other. So, in this video, I do just that: we make our neuron, duplicate it out until we have 20 of them, and then send some LFOs through that neural network. In the end, we use the output to trigger filter “pings” of five different notes.

There’s not really any kind of true artificial intelligence (or “deep learning”) in this neural network, because the output of the network, while it is fed back, doesn’t go back an affect the weights of the inputs in the individual neurons. That said, if we wanted machine learning, we would have to have some kind of desired goal (e.g. playing a Beethoven symphony or a major scale). Here, we just let the neural network provide us with some outputs for some Pure Data generative ambient pings. Add some delay, and you’re all set.

There’s no talking on this one, just building the patch, and listening to it go.

0:00 Demo
0:12 Building and artificial neuron
2:00 Networking our neurons
3:47 Feeding LFOs into the network
4:20 Checking the output of the network
5:00 Pinging filters with [threshold~]
8:55 Adding some feedback
10:18 Commenting our code
12:47 Playing with the network

Creating an artificial neuron in Pd:

Pinging Filters in Pd:

More no-talking Pure Data jams and patch-from-scratch videos:

Commodore 64 French House

Making some chiptune French house using the Commodore 64 and Alesis 3630.

C64 French House

Here, I’m using Paul Slocum’s CynthCart to turn my old C64 into a SID synthesizer. We run those licks into an Alesis 3630 compressor, side-chained to a kick drum (from an Alesis D-4), and then we have some pumping French house. Finally, we add some finishing touches with delay, reverb, and EQ in Logic Pro, as well as a cameo by an Electrix Warp Factory hardware vocoder.

Download the track here for free
:


More Commodore 64 sounds:

Patch from Scratch: Analog Feedback Loop in Eurorack

Patching up an analog feedback loop in Eurorack with some generic modules.

I don’t do a lot of videos talking about Eurorack for two main reasons:

(1) I’ve actually only been doing Eurorack for a couple years now, even though I’ve been doing digital synthesis and sound design for decades, and

(2) I don’t want my videos to be about any particular piece of hardware that you need to get (as always, I’m not sponsored by anyone).

But, the patch I put together in this video could be done by any number of modules, all I have is a sine wave, a ring modulator (multiplier), a reverb, a filter, and a limiter/compressor/saturator (anything to stop hard clipping). Put them together, feed them back, and you have some dynamic, analog generative soundscapes.

Previously, I’ve shown how to do the same thing in Pure Data, In Kyma, and in Reaktor.

Oh, and you can control it with an accelerometer too!

“Hard Sync” Oscillators in Reaktor 6 Primary

Creating retro sounds with hard-synced oscillators in Reaktor 6 Primary.

“Hard sync” is synthesis technique that uses two oscillators: when one oscillator (the “leader”) finishes a cycle, it resets the period of the other oscillator (the “follower”), creating a period at the frequency of the leader, but a timbre from the incomplete cycles of the follower.

This is a really easy way to create original, complex sounds, using just two oscillators.

I say “1980s”, here but check out this sound in the Cars 1979 hit, “Let’s Go” (played on a Prophet-5 Synthesizer).

0:00 Defining “Hard Sync”
0:38 Building a Single Oscillator
1:35 Adding the “Follower”
3:03 Changing the Pitch Relationship
4:40 That Hard Sync Sound
4:57 How it Works
6:30 Follower Lower than Leader
7:25 Adding an Amplitude Envelope
8:10 Adding a Filter (for a bit)
9:28 Closing, Next Steps

Reaktor 6 Beginner Tutorials here:

Ihatov MU (無) : Noise Music at the Hanamaki “English Coast”

Screaming noise improvisation on 54HP Eurorack at the peaceful Hanamaki “English Coast” (花巻イギリス海岸).

There’s a feedback loop going here with spring reverb and ring modulation, plus quite a bit of contribution from the After Later Audio Benjolin V2.

More “MU” on the Hanamaki English Coast: