It's almost taking electronic synthesis full circle. While the synths behind the past several decades of music achieve near-perfect replications of organic instruments using simple interactions between various signal frequencies (it's all math!), the Bastl Rack synth taps the organic world itself to do those modulations.
The forthcoming Bastl Rack modules are based on the academic research of one of Bastl's founders, Václav Peloušek, who describes his work as "Basic research in translating biological, mechanical and chemical principles into electronic musical instrument language and vice versa."
His thesis (published online here) goes into more detail, describing an extensive set of real-world events translatable into voltage fluctuations and thus music. A brief sampling: the shadows of fish in aquariums, a human pulse, the conductivity of skin, radiation, dripping water, a hamster on a wheel.
"Because of the nature of the language of the modular synthesizers which I used to represent the real world events, the errors and misconnections will occur on its own," Pelousek wrote. "This will result into new narratives or misinterpretation of ongoing narratives. I am especially interested in using such diagrams of systems as a score of a composition where a lot of interpretation is necessary. Pulse sensor might represent mankind, wind might represent the climate, fire might represent the wildness of the universe, radiation detector might represent a quantum aspects of the world etc."
It also might just sound really cool.