The Sony MDRNC500D promises to cancel out up to 99.1 percent of ambient noise through a new software engine. The day of 75 percent noise reduction through analogue methods is over, apparently.

It’s all well and good to make these amazing promises but does it actually deliver? Popular Science was lucky enough (or unlucky enough, depending how you want to look at it) to fly from Sydney to London and back in a week, with a side trip to Copenhagen for good measure. The Sony MDRNC500D came along for the 23 hour each way ride.

There’s nothing like the painfully loud hum of a Boeing 747-400 for 23 hours with only a one-hour break during a stop over. That’s the reality if you want to fly from Sydney to London as directly as possible. With Sony’s MDRNC500D that hum is meant to be a thing of the past. So armed with at least 70 hours of entertainment requiring headphones, we hopped on the plane and hoped for the best.

Let us first say that we don’t for a second believe Sony is lying when they state up to 99.1 percent of ambient noise is cancelled out. They can get into serious trouble if it was a false claim and it’s something that they would have done plenty of testing on to come up with that figure.

Does it sound like 99.1 percent of ambient noise is cancelled out though? Well, no, but a hell of a lot of it is, more so than most other headphones. The AI in the headphones is meant to be able to tell where you are (car, plane, bus, QANTAS flight that feels like it’s about to fall out of the sky) and adapt the noise cancelling technology to suit. It adapts on the fly so you don’t have to think about it.

On the headphones you can push a button that allows you to hear ambient noise again in case someone wants to speak to you, and you can switch the AI on or off as well. They’re a great set of cans, but for those expecting to jump on a long flight and hear almost nothing aside from your music (as we kind of were), that’s not going to happen. Remember, it’s only ambient noise that it fights.

In terms of comfort though, that’s where the MDRNC500D come into their own. You barely feel you’re wearing them and it’s certainly possible to keep them on for hours at a time. Our record was six after we fell asleep wearing them between Bangkok and London. They’re amazingly light as well for a pair of headphones that looks rather chunky. At only 195 grams you may as well be wearing a feather.

Power for the noise cancelling comes from a built-in lithium-ion battery as well as the option to stick a AAA into a small adaptor that connects to the cable. It’s handy to have the battery back up. Despite the 15 hours of life you will get from the lithium-ion battery, it’s very easy for the on/off switch to be flicked on if you are not using the supplied case. We did that and hopped on the flight back to Sydney with an empty charge. Luck we had the battery back up that delivers around another 10 hours of life.

And for the all-important sound quality? Great! Perhaps not $699 worth but great anyway. The bass was a little over powering no matter which equalizer setting you use but you can get used to it after a while. The fact that you can hear the bass so clearly over the roar of a jet engine is good enough for us.