Noise-canceling headphones

[Jerrysnb]

Here's a tip for you all:

My work area is surrounded by plumbing and household appliances, so I got some nice noise-canceling headphones. Now that I've started using them, I discovered that they can actually inject noise. I was wrestling with a constant low-frequency noise, something like a hiss taken down three octaves, when it occurred to me that the headphones might be at fault.

Sure enough, when I turned off the electronics in the phones the noise moved from inside the phones to outside. It was the fan noise from my computer.

[Paul Sanders (AlpineSoft)]

Interesting, thank you.  Can't say I've ever been tempted myself.