Brian Katz has provided the following links to demonstrate the concepts he discussed in our July 26, 2023 podcast.
Wave equation: https://en.wikipedia.org/wiki/Wave_equation
Colors of noise: https://en.wikipedia.org/wiki/Colors_of_noise
Tuvan: Alash
Spectrum/Polyphonic: Ana-Maria Hefele
Over/undertones: https://www.facebook.com/reel/1947626805590485