6 ms·

A popular YouTube channel recently recommended wearing Airpods with noise cancelling on the London underground because sounds routinely exceed 100 decibels some

A popular YouTube channel recently recommended wearing Airpods with noise cancelling on the London underground because sounds routinely exceed 100 decibels sometimes. Unless my understanding is flawed but the mechanical / energy potential is still reaching your ear drums, cochlear and in turn the hair cells. How would equalising the sound with an opposite sound help reduce the damaged caused here?

davesmylie 4y ago
The energy is reaching your ear in the form of sound waves. The ANC tech (when done correctly) is sending an antiphase (inverse) wave with the same amplitude but inverted phase timed exactly to the original sound wave. Effectively the two waves destructively interfere with and cancel each other out - it's not 100% but when done well is pretty effective for regular/consistent sounds
- akira2501 4y ago
  If it's not 100% for any particular reason then you are effectively adding noise and prolonging it's duration. I certainly wouldn't trust the speaker response to exactly match what the DSP is trying to produce over the wide range of audio that you could be listening to. It may even be worse if you're here a wide spectrum of noise as some components may be canceled while others, particularly high frequencies, may be amplified. I would always try to make passive cancellation work for my use case first, and only use active cancellation if it was absolutely required.
projectazorian 4y ago
If you’re wearing headphones you have a physical object blocking external sound waves from reaching your eardrums. Kind of like wearing earplugs but not as effective, although properly fitted airpods pro probably come close.
JonathonW 4y ago
Airpods Pro are not exclusively reliant on active noise cancellation to reduce noise alone-- the tips seal in your ear canal and provide passive isolation as well, similar to how earplugs or conventional IEMs (in-ear monitors) work. AirPods are not rated as earplugs and I wouldn't suggest relying on them alone to prevent hearing damage in loud environments (buy real earplugs for that), but they will provide some reduction in the noise that reaches your ears even when turned off. Also, active noise cancellation does actually cancel noise (it's not some kind of psychological effect making noise "invisible"); sound is a pressure wave and ANC works by moving air in the opposite direction to eliminate or reduce that pressure wave-- the mechanical energy from that sound is not reaching your ear drum if you don't hear it. This doesn't work perfectly, of course (the higher the frequency, the harder it is to eliminate with ANC for a bunch of acoustic and processing-related reasons), but, generally, if you're not hearing it, it's not reaching your eardrums and it's not doing damage.
- bobbylarrybobby 4y ago
  Is it possible that for brief moments (on the order of one oscillation, so for 10kHz it'd be on the order of 0.1ms) the noise canceling messes up and is in phase with the incoming sound, blasting your ears with double the amplitude before correcting itself? It could be for such a short time you don't consciously hear it, but it could still be enough to damage your ear.
  - deleted 4y ago
    [deleted]

davesmylie 4y ago

The energy is reaching your ear in the form of sound waves. The ANC tech (when done correctly) is sending an antiphase (inverse) wave with the same amplitude but inverted phase timed exactly to the original sound wave. Effectively the two waves destructively interfere with and cancel each other out - it's not 100% but when done well is pretty effective for regular/consistent sounds

akira2501 4y ago
If it's not 100% for any particular reason then you are effectively adding noise and prolonging it's duration. I certainly wouldn't trust the speaker response to exactly match what the DSP is trying to produce over the wide range of audio that you could be listening to. It may even be worse if you're here a wide spectrum of noise as some components may be canceled while others, particularly high frequencies, may be amplified. I would always try to make passive cancellation work for my use case first, and only use active cancellation if it was absolutely required.

projectazorian 4y ago

If you’re wearing headphones you have a physical object blocking external sound waves from reaching your eardrums. Kind of like wearing earplugs but not as effective, although properly fitted airpods pro probably come close.

JonathonW 4y ago

Airpods Pro are not exclusively reliant on active noise cancellation to reduce noise alone-- the tips seal in your ear canal and provide passive isolation as well, similar to how earplugs or conventional IEMs (in-ear monitors) work. AirPods are not rated as earplugs and I wouldn't suggest relying on them alone to prevent hearing damage in loud environments (buy real earplugs for that), but they will provide some reduction in the noise that reaches your ears even when turned off. Also, active noise cancellation does actually cancel noise (it's not some kind of psychological effect making noise "invisible"); sound is a pressure wave and ANC works by moving air in the opposite direction to eliminate or reduce that pressure wave-- the mechanical energy from that sound is not reaching your ear drum if you don't hear it. This doesn't work perfectly, of course (the higher the frequency, the harder it is to eliminate with ANC for a bunch of acoustic and processing-related reasons), but, generally, if you're not hearing it, it's not reaching your eardrums and it's not doing damage.

bobbylarrybobby 4y ago
Is it possible that for brief moments (on the order of one oscillation, so for 10kHz it'd be on the order of 0.1ms) the noise canceling messes up and is in phase with the incoming sound, blasting your ears with double the amplitude before correcting itself? It could be for such a short time you don't consciously hear it, but it could still be enough to damage your ear.
- deleted 4y ago
  [deleted]