I received these as a gift for Christmas. Put the battery in and they don't sound any different between on and off. Actually there is slightly more noise when they are powered on. Went outside where there was more ambient noise and there was no difference between on and off.

Nothing

It doesn't seem to do anything

these headphones are good and loud if your one of those people who loves loud music then i recommend

-brand; good sound quality; stylish

-too expensive -dont cancel much noise -too big

I travel extensively and purchased these to use while on planes. The previous noise cancelling headphones that I had, Sony NC60 were terrible for ham radio use. The NC500C is simply amazing to use for ham radio.

Sony introduced the MDR-NC500D at CES 2008 as the world's first fully digital noise canceling headphones, setting the $400 USD price tag accordingly. The all-digital design allows more flexibility in performance compared with analog models; you can dial in the appropriate level of noise cancellation...

The Sony MDR-NC500D headphones are suitable for music listening or movie watching, and they pack in some high quality noise-cancelling technology which makes them great for commuting or long-haul plane trips. Sound quality is good and the headphones are well constructed, but they are expensive.

Stylish and scratch-resistant exterior; comfortable padding; battery pack for extended use; good sound quality; noise cancelling works exceptionally well

Tight fit may annoy some; must be powered to work

The Sony MDR-NC500D headphones are suitable for music listening or movie watching, and they pack in some high quality noise-cancelling technology which makes them great for commuting or long-haul plane trips. Sound quality is good and the headphones are well constructed, but they are expensive.

Stylish and scratch-resistant exterior; comfortable padding; battery pack for extended use; good sound quality; noise cancelling works exceptionally well

Tight fit may annoy some; must be powered to work

The over-the-ear MDR-NC500Ds are, according to Sony, the world's first digital noise-cancelling headphones. Lightweight and extremely comfortable, they certainly provide the best noise-cancelling experience we've had to date.

Lightweight construction; Fantastic noise-cancelling performance

Expensive; Weak bass response

Sony is making a lot of noise about its latest noise-cancelling headphones. The usual way this type of headphone works is that the device "listens" to the ambient noise and broadcasts a "mirror image" of the sounds into the wearer's ears, thus neutralising background noises.

Sony is certainly no stranger to the headphone market. The company's portable line may very well be the most popular after-market earphones. It has quite an array of full-size "cans" as well as a decent selection of noise-cancelling models.

Superior noise cancellation; Solid sound quality; A plethora of useful extras; Including a battery pack for extended use

Cannot be used without noise-cancellation activated; Tight fit may be uncomfortable for some users; Expensive

Record labels, hammered by ever plummeting CD sales, see a ray of sunshine in the recent minor renaissance in vinyl records, whose sales and production continue to steadily expand. The reason for this 33 1/3 RPM nostalgia?

Noise-cancellation is adjustable to your environment and a monitor switch is handy for temporarily hearing external sound; And external battery box is handy when the built-in batteries wear out, but they work nonstop for half a day without a recharge

Handy external battery box adds to the weight and bulk of the protective carrying case as does the power brick also enclosed; Some bass sounds played at high volume cause ear splitting distortion