I read into this the first time i wore noise cancelling headphones shooting. They were such a leap in technology and efficiency I had to find out how it was done.
To this day I feel like its one of the most amazing technological performances ive ever experienced. It was the first time i could appreciate the sheer speed that pcb’s can process information and react. My head is resting on the stock of a rifle and in the nano second it takes for the gunshot’s sound waves to hit the external microphones, they instantly process the sound, identify it as a hazardous wavelength, and activat the sound surpressing function, ALL BEFOR THE SOUND WAVE TRAVELS FROM THE OUTER SHELL OF THE EARMUFFS TO YOU EARDRUM.
Even after i r3ad how they work i refused to accept it. I was hellbent convinced they worked like check valves where it had to be mechanical. The soundwave hit the floating ball and force it to seal off the inner microphone of thr headphones. NOPE dead wrong lol
It takes 29 microseconds for sound to travel 1cm. That’s eons in electronics world. The phone you use is probably doing an operation every .0005us or faster.
Also, that style of headphone is a lot less complicated than ANC headphones. They just have a microphone/speaker pass through and an envelope-follower that detects peaks in the audio wave. If the peak is over a threshold, shut off the speaker. The headphones block the sound just like classic hearing protection.
They also may potentially benefit from a small buffer, so everything you’re hearing is a little delayed. Gives the circuit more time to react, though I’m not sure that’s necessary.
Are you talking about noise canceling headphones or earmuffs with audio pass through? I have both and they’re very different things. Noise canceling headphones are not rated for hearing protection (most of the time) and do use active noise canceling. But that can’t fight the pressure of a gunshot. Earmuffs with audio pass through are pretty simple. They’re just regular ear muffs that are rated for hearing protection and just have a mic that plays what it picks up to a certain level.