Tired by the hum of plane engines? Distracted by the office airconditioner? Dave Bullard checks out the current crop of active noise cancelling headphones.
The concept of having headphones that can cancel outside noise has been around since the 1950s, but they haven’t been a mainstream consumer item until fairly recently.
Bose, which developed the first active noise-cancelling (or NC) headphones, had a monopoly on the consumer market for many years, but there are now many options to choose from.
For those of you new to the concept, active NC headphones let you reduce outside interference so you can hear your music or movies better in noisy environments, concentrate better on a task, reduce fatigue on long flights and more.
They do this by using tiny microphones – mounted outside or inside the earcups – to measure unwanted noise, then generating an inverse wave that effectively cancels the noise. All this is done in very close to real time – the incoming audio signal (from your iPod, plane seat or whatever) is delayed by a split second to allow the circuitry to generate the new wave pattern and give you the best sound under the circumstances.
The NC circuits can affect the music you’re hearing, so you generally wouldn’t buy a set of noise-cancelling ‘cans’ for non-noise-cancelling use (most won’t work without the NC circuits turned
Not all NC headphones are created equal. For instance, while all are capable of eliminating steady background noises – such as aircraft cabin noise or the hum of an airconditioner in an office – only a few have the circuitry capable of approaching the elimination of shorter, sharper noises such as voices or a barking dog.
Most have a slight hiss when turned on, so check that this disappears when audio is played.
If at all possible, try the headphones before you buy. What I find uncomfortable you may well like, and vice versa.
And, finally, be aware that when a manufacturer says its headphones are ‘noise cancelling’ it might just mean ‘sound isolating’ or ‘noise-reducing’, which they do using tight-fitting or thick earpads or earbuds. To get the best results you want ‘active’ noise-cancelling headphones, which use the circuitry described above.
This Lab Test originally appeared in the May issue of Australian Macworld magazine.