Question

There are headphones on the market that advertise noise cancellation technology. Headphones that eliminate or reduce outside noise have been used for jobs on aircraft carriers and car racing pit crews for a long time. These headphones produce an anti-noise wave that is designed to meet other noise waves. The result is not much more than a faint hiss. Use what you know about the interaction of waves to explain how this is possible.

Answer 1

the cancelation pf headphones works as the equalization done by the equalizer of your audio system in a car for example...

the simplest way to understand that is to take the superposition of waves...if you superpose two waves that the one's amplitude is negative and the others amplitude the two cancel outs...

what is done in effect is the use of an inverse filter that cancels out the somewhat complicated characteristic of the headphones (in the frequency domain from about 20 to around 20kHz that is the frequencies our ears can hear).the inverse filter must be designed for the specific characteristic of each special brand and model of headphones.the frequency characteristic of the headphones is usually tested in real ears or in dummy heads by use of current couplers.

Answer 2

*and the other's amplitude is positive*

Answer 3

For Solving this Question, I would like to ask you that, do you have the detailed conception of : Sound ans Waves