[Discuss] [kind of off topic] noise canceling headphones

[blu at nedharvey.com (Edward Ned Harvey (blu))]

There's a major difference between
Active Noise Cancellation
and
Passive Noise Isolation

Passive can be extremely cheap, block out everything except what the headphones are generating. Active is usually expensive, and usually does a really good job of blocking periodic or repetitive noise waves, like machine noise and hum from noisy equipment. I've often heard people say their active (Bose) headphones allow peoples' voices to pass through while blocking machine noise and stuff like that.