Where did the noise go?

I recently purchased the Sennheiser PCX300, to replace a panasonic noise cancelling headphones that I had--mostly because of comfort, as they were too big and would be somewhat painful if worn for extended periods of time.

The PCX300 are an upgrade from the PCX 250. Apparently, they have improved the noise cancellation a little bit, but the main difference seems to be the increased audio response, from 10-2100 Hz, up to 8-21,500 Hz. Otherwise, there isn't much difference.

What I've noticed so far: Absolutely no hissing when the noise cancelling function is turned on. This was a problem with the Panasonic model I previously had. The noise cancelling is excellent. I use this mostly in the Gym, where I want to listen to my own music without the annoying noise of treadmills, chatter, and punk rock that blares through the radio set up by someone in a corner. If you're like me, you've probably had to crank up your stereo headphones so that you could hear your own music. For this setting, it works very well. I'm able to listen to my stuff without the distraction of everything else, and turn down my volume down to a low, safe level. Everything else just goes away!

Sound wise, I'd say the headphones are good---as good as any decent headphones without the noise cancellation mode on. I have a set of earphones that came with a sony portable CD player that cost about $60 bucks, and comparing the sound of both, I have to admit that they sound the same. It's good, but not earth shattering.

HOWEVER, I've noticed that if I turn on the noise cancellation mode on, the sounds is greatly improved...even in a quiet environment--especially the low tones. I've used it to watch movies on my laptop, and recently on my newly acquired MP3 player (a JVC XA HD500 --6GB player) and the sound is fantastic. I am very pleased.

Comfort/portability wise: Headphones are very lightweight and fit over the ears comfortably. There is a clip on the battery holder, so that you can tuck that away. The cords are long enough so that you won't tug on the cords accidentally when moving around. The headphones fold down to a nice compact size--unlike the Panasonic model I previously owned, or the Bose models.


The nuts and bolts:

Supplied with two adaptors for in-flight entertainment systems (adaptors: 1/4" (6.3 mm) stereo jack and 3.5 mm double mono jack)
Includes protective soft case
Batteries included
2-year warranty
Delivery Includes
1 PXC 300
1 transport case
1 adaptor 6.3 mm stereo
1 adaptor 3.5 mm double mono
Batteries
1 user manual

Technical Data
Nominal impedance 300 Ù
Jack plug 3,5 mm stereo
Transducer principle (Headphones) dynamic, closed
Ear coupling supra-aural
Cable length 1,8 m
Weight w/o cable 65 g
Frequency response (headphones) 8.....21500 Hz
Sound pressure level (SPL) 107 dB (SPL)
THD, total harmonic distortion 0,1 %
Operating time (Battery) 80 h

You'll notice that the PCX 250 had a frequency responce of 10-21000 Hz.