Synthesizers and the Brain

Over the many years I worked with synthesizers, I enjoyed musical sounds, interesting psychoacoustic effects and compared the construction of synthesizers with the construction of the human brain. This is a more useful metaphor if you combine a sound mixer with sound synthesizer, capable of producing sounds in complex patterns. A synthesizer is built from function-specific modules that are linked together to produce the final results.

When I was first studying electronics, I constructed a synthesizer from modules that each performed one function. The modules had jacks on their front panels so that each could be connected to other modules by using patch cords. To generate musical sounds you connected a piano-like keyboard controller that sent out a different voltage from each key to a voltage controlled oscillator that generated the sound waves at the appropriate pitch. The oscillator was typically connected to a voltage-controlled amplifier that was in turn controlled by a ramp generator, since musical sounds emerge and decay within an amplitude envelope. To finish a convincing musical sound, many modules would be connected in a single path.

This approach to synthesis provided an example of a modular system that could be compared to explanations of how the brain works. Functions of different modules are described. The anatomic knowledge of the brain connects modules but cannot explain exactly what these connections do. You could imagine that there are different kinds of connections and construct theories of function accordingly. Neuroanatomy describes complex networks of connections that are often parts of webs and meshes more than point to point discrete connections, although point-to point connections do exist and are the most obvious.

I have ongoing attachments to two sophisticated synthesizers, the Korg Trinity and the Proteus 2500, both magnificent electronic devices that contains the equivalent of hundreds of modules and thousands of patch cords. Rather that actually building modules physically and connecting them with real wires, these synthesizers simulate modules and patches by using a digital computer to calculate what the output would sound like if you had a set of modules connected in a certain way. On the Trinity, you choose the "modules" from menus on a touch sensitive screen; then you choose values for many parameters that control the modules and connect modules to form the "patch" or sound that emerges in stereo from the output jacks of the synthesizer.

The sound can be a single instrument played expressively, an entire string section or a complex and evolving mixture of sound effects suitable for a Star Wars soundtrack. The synthesizers with virtual modules and dense, variable inner connections provide a modular interconnection concept that can be applied to studying the brain. You combine the knowledge of what each module does with knowledge of how different connections add to, modify and combine the function of individual modules.  

More About Trinity and EMU Proteus
Sound Processing in the Brain
Analogue Synthesizers
Low Frequency Oscillators