I have been thinking and learning about sound and noise control/isolation for a long time. I am quite sure that active noise cancellation in real domestic environments is impossible. Simple physical isolation will always be cheaper and more effective. The idea of portability is founded on an overly simplified and ancient demonstration of sign waves cancelling each other, and fataly leave out how human hearing actualy operates, and there are now indications that the very best active noise cancelling headphones, are working, but with side effects that are disorienting, and likely very bad for your health and brain.Do the deap, deap dive into just how sophisticated human hearing is at discerning usefull information in an increadably complecated environment, and the fact that there is NO OFF SWITCH, this isn't just an osiliscope excersise, your brain is fighting furiously to figure out what that wierd sound is, please be nice to your brain and dont feed it an endless unatural, impossible in nature, signal. 3 years of sound engineering in a past life, and still loving sound/music/audio and searching for implimentable solutions to NOISE