Finally we have a pair of active noise cancelling headphones that offer some competition to the Bose Quiet Comfort series. Panasonic's RP-HC500 are over-the-ear headphones that offer reasonable sound quality combined with active noise cancelling. Audio purists won't be satisfied with the sound quality, which lacks the clarity and detail of more advanced Hi-Fi headphones, but the HC500's produce quite smooth audio that is more than adequate for the average listener.

The primary feature of these headphones is their noise cancelling capabilities and in this regard they perform quite well. External sound is blocked out in two separate ways. First the headphones completely enshroud your ears, so little sound can actually penetrate. Secondly the RP-HC500 also has active noise cancelling, which works by using microphones to record external noise, and then the headphones play opposing sound through the drivers in order to cancel the sound out.

Our tests showed the active noise cancelling on this model worked quite well. In our office environment, simply wearing the headphones blocked out a good quantity of external sound. When we fired some tunes up, everything else completely disappeared. We did however notice a little sound leakage, even when wearing them properly, which is strange for a pair of noise cancelling headphones. It was still better than the leakage from many other pairs of headphones, but if you're after absolute silence so as not to disturb your colleagues, then you may need to look elsewhere.

We also took them on the road and tested them in a variety of different and more practical scenarios. While unfortunately we couldn't use them on a flight (one of the key areas where noise cancelling products shine) we did manage several rickety bus trips, which are almost as demanding. The RP-HC500 performed quite well in this regard, shutting out a lot of the rumbling of the engine. However it didn't manage to remove it completely and overall we found the noise cancelling slightly inferior to that of the high-end Bose headphones.

Sound quality is an area of slightly less importance when it comes to noise cancelling headphones, however we still rate it as an important factor. Our first impression of the RP-HC500s was quite good. They produce a smooth, flowing sound that makes for great background listening. However a more detailed analysis revealed a lack of refinement across the whole sound-scape which detracted from the overall experience quite a bit.

There was a general lack of clarity or finer definition across the bass and mid range, which meant the overall sound wasn't as detailed as we'd like. There was a good amount of bass and it extended deeply, although it could have been a little tighter. Meanwhile the mid range was a little too strong for our tastes although it was the best sounding element of the music. The highs were quite good with a relatively sweet sound, although they did get a little bright at some points.

The soundstage was decent but not noteworthy. We have noticed a tendency for noise cancelling models to struggle a little in this area compared to their Hi-Fi brothers, and the RP-HC500s were no exception. Our music sounded a little two dimensional, comparable to a small room or studio.

As with most noise cancelling headphones, comfort was somewhat of an issue. The suction effect commonly felt in other, similar pairs, was again present here. It isn't a huge issue, but it does take a little getting used to. Aside from that they were quite comfortable, resting snugly on the ears and providing adequate padding.