For so long Bose's Quiet Comfort series has dominated the noise cancelling headphones category. Other companies have tried to break their hold over the market, but Bose's combination of good audio quality, comfortable design and some extremely strong marketing has meant they've remained the kings. Now it's Philips' turn to have a crack. Their SHN9500 headphones are very similar to Bose's in both design and performance and while they may not knock the champ from its podium, they do offer a solid alternative.

The audio produced by the SHN9500s is impressive. If you're after a true audiophile noise cancelling experience, we'd recommend a pair of high-end IEMs (In Ear Monitors), but for those who prefer an over-the-head design and active noise cancelling, this model will not disappoint.

Bass is the most prominent element of the sound. It is incredibly powerful and actually manages to rumble the headphone cups a little, which is something we don't often experience. The low note decays quite slowly which gives a dark sound. However, unlike many other bass heavy models, it isn't too bloated. We still wouldn't recommend the sound for styles like jazz or rock (which are better served with great treble and mid ranges), but hip hop and dance music listeners should appreciate it.

There is a reasonable amount of detail in the mid range and the treble notes come out sweet and clear. They aren't overshadowed by the lower register, which is common on bass heavy models. Overall the sound is quite energetic and slightly gritty.

The cups are constructed out of soft pleather (plastic leather) and are comfortable, even after long listening sessions. Meanwhile the headband is a little flimsy, built mostly out of plastic, although it is a still sturdier than Bose's offerings.

One of the key differences between a model like this and the high-end IEMs that we recommended earlier is that this unit has active noise cancelling technology, which means it analyses what sound is coming in from outside and compensates for it by playing opposing sounds through the headphones. This has the somewhat spooky effect of almost completely isolating you from external sounds. During our testing, it operated very well and should be perfect for blocking out annoying sounds such as bus motors, jet engines and co-workers.