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Need noise cancelling headphones recommendations
(lemmy.world)
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Edit: See sushibowl's explanation below why this is incorrect
What do you mean that blocking sudden noise in technically very challenging? I might be wrong, but from what I have gathered is that ANC is based on playing a "negative" of a pressure wave picked by the microphones in phase with the original wave. Thus it has to react to all sounds in the time that the pressure wave travels from the microphone to the ear, so it shouldn't matter whether the noise is constant (airplane) or sudden (gunshot).
Of course if the headphones have some kind of pass-through active, then it might take a while until software decides to activate ANC, but that is not a limitation of ANC itself
That's the theory, but it's almost impossible to do in practice. Your microphone and speaker are imperfect at capturing and reproducing sounds. The phase timing is incredibly sensitive. You only have milliseconds to do the processing and generation.
That's why practical noise cancelling relies on feedback loops. A second microphone inside captures the result of the cancellation, and based on that adjustments can be made to the negative signal. This allows you to correct for lots of sources of error and achieve quite a good result. Of course, for a sudden noise like a gunshot, by the time the feedback loop can really kick in, the noise is already over.
Oooooh that makes so much sense, I had been wondering why lifting the earcup slightly doesn't amplify the sound, but that explains it. Thank you for the clarification!