It's been raining a lot here lately & that reminded me of this musician.
The heterodyne effect occurs when two frequencies are mixed together in a nonlinear device. Such as the mixer circuit of analog radios, analog TVs, & also in the human ear. FOUR frequencies result. The original two, the sum, & the difference. I sometimes wonder what doctors Fletcher & Munson would say about the interactions of all the frequencies floating around the airwaves these days. https://en.wikipedia.org/wiki/Equal-loudness_contour
This first clip clearly demonstrates the effect. If you want to make all the neighbors think the evil UFOs are arriving point some really good speakers outside & crank up the volume at 4am. It was great fun when this was first recorded but that prank might not end well now. Proceed at your own risk. This is super freaky with good headphones on.
Argue for your limitations and they are yours forever.