Conclusion: Above average noise reduction, especially for low frequency sounds. Construction is flimsy though. Sound quality is really good. I read some people hear a hiss with these headphones but I have never heard it.
Conclusion: The noise cancellation is great. Comfortable earbuds. Have used it in planes and on treadmills. Cons: the cable from the earbuds to the unit is too short to clip the unit onto your belt. Will not 'pass through' audio when turned off. The slide volume control keeps it from accidentally getting changed, but then is difficult to 'fine' tune.
Summary: Comments about Panasonic RP-HC55 Noise Canceling Earphone: A good earphones. Very good noise cancellation capability as advertised. The only problem is that it creates unpleasant static noise when using it for running on a treadmill.