Higher-end aviation headsets count on Active Noise Reduction (ANR) to achieve a quieter flight environment. Manufacturers use this technology to give you the perception that sound is reduced.
These are the 2 key components of how sound is controlled when you wear a headset while flying:
1. Passive noise control provided by the fit of the ear cup around your ear
2. Active noise control from the acoustic components of the ANR process
Headsets reduce sound passively through fit. This is achieved through design of the material the ear cup is made of as well as the amount of force the ear cup exerts on the area surrounding your ears.
All headsets – ANR or not – reduce and filter the sound this way.
ANR technology goes beyond that and attempts to kill the rest of the sound that creeps into the ear cup environment.
Here are the components that make it work…
1. Microphones to pick up ambient noise
2. Electronics that match the sound and create an opposite sound
3. Speakers that broadcast the opposite signal into the ear cup environment to cancel the ambient noises
The way this all comes together is the microphones first sense the frequency and amplitude of the noise in the ear cup.
The electronics in the headset understand and reproduce opposite wave forms of the same sound and communicate that to the speakers.
The speakers then send that opposite wave sound into the ear cup to cancel the perception of noise.
Obviously, this all happens real time – a delay in sound delivery would make the ANR exercise pointless because you would hear feedback otherwise.
In order to get real cancellation the electronics must be sophisticated enough to pick up on subtle differences in cockpit noise. The more perceptive the electronics, the greater the accuracy of the noise cancellation.
The toughest job for headset manufacturers is to draw a balance between the passive filtration of sound via the clamping force of the ear cups and the ANR. Obviously the more effective the passive noise control provided by the ear cups themselves the less work the ANR technology must perform.
The problem is the passive steps can make the headset uncomfortable to wear, so there are tradeoffs the designers must make.
The degree to which they get the mix of passive and ANR right determines their marketplace success.
Higher-end headsets tend to be very comfortable and do an excellent job of cancelling sound. The choice for you in which headset you buy is more one of personal preference. No one headset works best for every head and for every flight environment.