When thinking of sound quality from the HN-505 you have to consider the price tag and usages. At $40 you're not going to get a concert hall on your ears and the HN-505 cannot compare to any of the chunkier offerings being flaunted around the pages of this feature. That is not to say however that the HN-505 headset provides poor sound quality - it's just that it's not spectacular.
The sound is clear and there is no distortion even at high volumes. Music playback is flawless and for games the 505 lives up to the task, though if you're a serious gamer (and particularly a mobile laptop one) it will leave you feeling a bit wanting. Saying that however we have played with far worse over our ears and after coming in with very low expectations for game play sound quality we were pleasantly surprised with the performance put forward by the HN-505.
The noise cancellation is very well done blocking out a lot of incidental noises that can annoy and interrupt on smaller headsets. Activate noise cancellation on the HN-505 and you need not worry about the birds singing, and it even does a decent job of eliminating things such as car engine noises on road. It won't totally cancel out all noises, so is more of a noise-reduction feature but one that is none the less rather effective. The only gripe we had with it was the fact that you really do have to turn on the noise-cancellation to get the sound to decent volumes - it's rather muted without the noise cancellation on, which could prove problematic when the battery for it begins to go on the blink.
We can't help but feel sorry for the HN-505 in this feature as it is really the lame duck when compared to the other bullies in this particular playground. However, for the niche that it is fitted into the headset has some serious advantages over the big boys. Its portability and noise cancellation features, as well as the price tag, make it the best buy for someone looking for a cheap, effective headset on the go. It should be noted, however, that the HN-505 does not come with a microphone making it unsuitable for anyone looking to use it for VoIP connections.