I know the basic theory - that they listen to the ambient noise then play the inverse waveform into your ears to cancel it out. However, it seems to me that this would only work if the ambient noise was a regular waveform. What if it’s not? Can ENC headsets cancel out a conversation, for example, or the noise of a busy city street? If so, how do they do it?
I can’t really answer your question fully sorry. However, a complex waveform is not difficult to reproduce. Stereo speakers do it all the time. To reverse polarity is simply a matter of changing a couple of wires. You can do it with your stereo by wiring one of the speakers the wrong way. The speakers would then be out of phase with eachother.
Thanks. My question wasn’t so much about the actual production of the waveform though.
Given that many types of background noise are essentially random, how can you produce the “inverse” if you can’t tell what the waveform will be like in the next second, millisecond, nanosecond etc. I presume that there’s a delay, however small, between the processor analysing the sound and actually producing the inverted waveform. Is the delay so small that the change in the ambient noise waveform will be negligible? (this is the only explanation I can think of…)