Mark got in touch to find out how noise cancelling headphones work. Can they damage your ears by playing back loud background noise? Fanny Yuen spoke to Trevor Cox to cut the rumble...
No. Noise cancelling means just that. alancalverd, Thu, 19th May 2016
It is true that noise-canceling headphones are optimized for reduction of noise in the human hearing range (approximately 50Hz to 20kHz for a child).
An engineer described NC as follows in a way I found easy to understand. The goal is to stop the headphone housing from vibrating. Ordinarily, noise strikes and vibrates headphone material, which in turn vibrates the air on the air inside, and so sound passes to the ear. Where the headphone material not to vibrate, then no outside noise can pass through. Active noise cancellation stops the headphone housing from vibrating, by doing all it can to hold the material dead still.
The hearing function is quasi logarithmic hence the efficiency of the noise cancelling can be expressed in db how good are they ?.