Anr Question

[Bladestrike]

A fellow pilot scorned my ANR for the following reason, and thinking about it, I couldn't say he was wrong.

 

Anybody know anything concrete about this?

 

The active reduction works by sending an "out of phase" signal to the eardrum thus eliminating (cancelling out) the noise, but isn't the eardrum being subjected to twice the abuse....one being the original noise, second being the "out of phase" noise that is out of sync to cancel the ear's recognition of the original noise?

 

Or something like that.

[shaggy]

if my understanding of rudimentary physics is correct i would say "no". sound is a wave and if there are two waves of equal amplitude but opposite phase, then they should be cancelled out when they are introduced to each other at the headset not at the eardrum. i could be wrong and stand to be corrected if so.

cheers

[Skidz]

ANR consists of two active components:

 

A microphone, that captures sound in the earcup of your helmet or headset, and a speaker, that emits a signal that is of equal amplitude, but 180 degrees out of phase. The ANR circuitry also makes sure signals coming from comms is not filtered.

 

The effect is to cancel the noise, not mask it. Your fellow pilot was probably thinking about white noise, which is basically broad-spectrum low-volume noise used in places like shopping malls and office buildings to absorb and attenuate echo. I've worked in a white noise office. The feeling is a little like when you watch Star Trek and there's this constant background noise...

 

Here's a page on AVweb on ANR:

 

http://www.avweb.com/news/avionics/183221-1.html