Noise canceling headphones?

[Nadeac]

What do they do ?

Thanks Mark

 

[John Duncan]

Use electronics to cancel external noise (like traffic and commuters). Here's wikipedia with the science bit..............

As distinct from noise isolating headphones, which shut out extraneous noise by making the seal as good as possible - by being right in your ear, for example, or covering them as tightly as possible.

 

[Anonymous]

What?