I've contacted the head of engineering at Cascade Designs and hopefully he'll get back to me on it. Personally, I haven't heard this in my pots, or, rather, haven't 'noticed' it. I agree with phat that most stoves make some kind of noise (screeching, whistling, poping, etc.) at some point during the boiling process. My guess is that it's the metal fins heating up which does cause the molecules in the metal to vibrate which, in turn, has the potential to make a specific, short, 'screeching' noise. In the case of the Gen 2 Reactor (laser-welded fins vs. forged fins of the 1st generation pot), the fins are much thinner and are welded on which could cause some vibration and noise (no concern of durability I assure you). The newer pot is much lighter and is as durable and efficient as the older pot.

I'll play with mine and see if it makes any sound as it heats up. I'll let you know of my results. I'll also fill you in if I hear anything from Cascade Designs.