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Review: Noise-cancelling Headphones
When you travel a lot and for a long time, you sometimes want to listen to music or watch a film in a relatively quiet environment. Unfortunately, high-speed trains or planes are noisy, very noisy. Which is where noise-cancelling headphones come in.
Tristan François
Translator: Jack Sims
Updated: September 2, 2010
Translator: Jack Sims
Updated: September 2, 2010
Controlling noise causes noise!
Don't believe that noise control works perfectly. Quite the contrary! The basic principle may well be disconcertingly simple but things are much more complicated in practice.
Worse, not only, in the majority of cases, is the low end of the spectrum filtered much more effectively than the high end (this isn't too much of a problem as it's the low end that is the most disturbing, with high-pitched sounds naturally filtered by the insulation material in headphones) but the electronics themselves are often the source of the unwanted noise.
Though not as loud as exterior noise, this electronic noise comes straight to your ear. Not everyone is sensitive to it to the same extent and how present it is depends on the headphones you're using. If possible make sure you try before you buy!
Though not as loud as exterior noise, this electronic noise comes straight to your ear. Not everyone is sensitive to it to the same extent and how present it is depends on the headphones you're using. If possible make sure you try before you buy!
When you want to eliminate an unwanted noise, two solutions are available to you insulate the source of this parasite from the receiver, or eliminate the source.
Soundproofing
The first solution is easy to put into place in this specific case. You simply have to plug your ears. If you want to broadcast sound nevertheless, you just have to put the sound transmitter behind whatever is blocking your ear. This is exactly what in-ear headphones do: the part generating sound is surrounded with a piece of rubber, silicon or memory foam, which obstructs the ear canal.
There are two problems with this however. Firstly, though the noise is filtered, it isn't completely eliminated and secondly, the frequencies that are filtered depend on the materials and thickness used.
Active noise control
So let's look at the second alternative, which is eliminating the source. While getting your neighbour to turn down the volume by banging a broom on the ceiling may be effective, when you're in a plane this isn't so easy.
The solution that was invented for the aeronautics industry a couple of decades ago is extremely simple. You detect the unwanted sound waves and inject the exact opposite into the audio signal heard by the listener. The two superimposed waves then work as a perfect mirror and cancel each other out.
OK, but in practice, it's more complicated as you have to calculate the passive attenuation of the headphones themselves, the resonances of the materials used, the sensitivity of the human ear and so on and so forth. And (why not!?) how about making it so that ,as a plane passenger, I no longer have to listen to the noise of the engines but can hear the hostess who's offering me a soda? This is what all the R&D is currently working towards in this domain.
Without forgetting that, while an aeroplane, helicopter or space ship pilot wants, above all, to be able to hear those who are trying to communicate with them without being deafened by the noise of engines, the mass user is looking for quality sound.
What you'll need to take into account
Although noise-cancelling headphones aren't the lightest headphones around, because of all the electronics they use, they are still travel headphones, which means you'll want them to fit into a compact, though sufficiently protective, case. Also, a plane socket adaptor will come in handy, as will a charger with various national plugs, if the headphones are battery operated.
Soundproofing
The first solution is easy to put into place in this specific case. You simply have to plug your ears. If you want to broadcast sound nevertheless, you just have to put the sound transmitter behind whatever is blocking your ear. This is exactly what in-ear headphones do: the part generating sound is surrounded with a piece of rubber, silicon or memory foam, which obstructs the ear canal.
There are two problems with this however. Firstly, though the noise is filtered, it isn't completely eliminated and secondly, the frequencies that are filtered depend on the materials and thickness used.
Active noise control
So let's look at the second alternative, which is eliminating the source. While getting your neighbour to turn down the volume by banging a broom on the ceiling may be effective, when you're in a plane this isn't so easy.
The solution that was invented for the aeronautics industry a couple of decades ago is extremely simple. You detect the unwanted sound waves and inject the exact opposite into the audio signal heard by the listener. The two superimposed waves then work as a perfect mirror and cancel each other out.
OK, but in practice, it's more complicated as you have to calculate the passive attenuation of the headphones themselves, the resonances of the materials used, the sensitivity of the human ear and so on and so forth. And (why not!?) how about making it so that ,as a plane passenger, I no longer have to listen to the noise of the engines but can hear the hostess who's offering me a soda? This is what all the R&D is currently working towards in this domain.
Without forgetting that, while an aeroplane, helicopter or space ship pilot wants, above all, to be able to hear those who are trying to communicate with them without being deafened by the noise of engines, the mass user is looking for quality sound.
What you'll need to take into account
Although noise-cancelling headphones aren't the lightest headphones around, because of all the electronics they use, they are still travel headphones, which means you'll want them to fit into a compact, though sufficiently protective, case. Also, a plane socket adaptor will come in handy, as will a charger with various national plugs, if the headphones are battery operated.
