What is the difference between passive and active noise?

Question

I'll readily admit I'm ignorant to this. I'm autistic and trying to find a solution for my extreme sound sensitivity. What is what and which would benefit me most? I've tried industrial ear-muffs and I'm using noise-cancelling headphones right now. I'm experimenting to find out what product(s) will best serve me. In reading about these materials, I hear these 2 terms but they aren't explained (at least in enough laymen's terms for me). Will someone well-versed in the audio-technical field please answer? Thank you.

Answer 1

Noise is any signal that is "random".
White noise is considered the extreme case, since it has a frequency response across the whole spectrum.

In passive noise filtering, you design circuits that have a frequency response close to that of the noise you try to remove. For example, you use low pass filters for low-frequency noise, etc.

In active noise filtering, used in noise- canceling headphones, you actually generate counter noise that counter-balances the original noise. The two signals "cancel-out" and you have a noise-free signal.