Why have gadgets (headphones and players) with active noise cancellation been in existence for a long time, but there is no separate ACP module?

Question

Headphones

I will describe the issue from the domestic side. I have closed-type headphones, I'm quite happy with them. However, in transport, the noise still does not allow you to enjoy the music, I think this is familiar to many. I don’t see the point in buying separate headphones for transport. The idea was to make a DIY ACP module that could be used with any headphones. I would like to know your thoughts on this matter. What are the pitfalls to expect from the technical side?

Answer 1

ACP is not a universal silver bullet, it is strongly tied to the specific design and components of the headphones. ACP transplanted to other conditions will not work.

Answer 2

Gadgets (headphones and players) with active noise cancellation have been around for a long time

Well, well ... Another victim of smart-ass marketers.

Answer 3

Well, as it were, the essence of technology - a microphone in your ears catches what should reach your ears, and gives you an antiphase in your headphones. As a result, zero.
I don’t know anything about players with noise reduction, it’s a rather gloomy concept, it turns out that the microphone should be on the player and how it will distinguish the rustling of pants from real noise, I don’t understand something ... But there are ears with active noise reduction.
On the issue of technical implementation, here is a link to the button accordion but warming my soul service lmgtfy.com/?q=diy+active+noise+cancelling