Background noise is a part of modern life. Whether it’s healthy or harmful, though, is sometimes a matter of perception — one man’s invigoratingly vibrant ‘sound of the city’ being, after all, another man’s hellfire corner of the ‘concrete jungle’ — most of us regard the tranquillity of a rural retreat a major stress-busting benefit. However, people unable to enjoy regular exposure to a natural nirvana surely must have wondered about the benefits and effectiveness of noise cancelling headphones as a possible means of respite from background noise.
The technology most noise-reducing headphone sets employ is based on the acoustic principle of noise-cancelling frequencies. Known as active noise control (ANC), this feature depends upon the creation of a new sound signal designed to cancel out an existing, unwanted signal. To achieve this, the new signal must be the same strength and frequency as the original, except that its sound wave is inverted – the newly generated wave thus being a reversed, ‘mirror-image’ clone of the original signal. When the new signal is added to the original (unwanted) signal, the troublesome sound is effectively cancelled out.
Though the technology necessary to build noise-cancelling headphones has been available since around 1986, active noise reduction has only appeared in the hi-fi music world in more recent times. That said, there are many situations in daily life where the ability to neutralise annoying background noise is perhaps more focused on the benefits to health and well-being – air travel being a prime example.
In-flight noise can be irritating to passengers, and since it mostly consists of regular, low-frequency rumbling sounds, it’s relatively easy to negate these effects with ANC headphones. As a result, many luxury airline flights and some first-class rail journeys, offer passengers the benefit of noise cancelling headphones. Given their advantages in these situations, ANC headphones could be equally useful for the tube and other public transport journeys where there is a constant low-frequency background drone.
ANC-equipped headphones tend to be less effective where the background noise is intermittent, or where it consists of a mix of sounds right across the frequency spectrum. Mid-, and especially high-range frequencies, are much harder to wipe out, which means air-travel passengers lose the reverberating roar of the engines but will rarely miss the in-flight announcements. Unfortunately, it also means the crying baby in the seat behind will still be audible too!
Audiophile heaven may, or may not, be enhanced by active noise reduction depending on what your listening priorities actually are. The advantage, of course, is the reduction in background noise – though it’s important to note this is not consistent across the whole audio spectrum. Despite this benefit, many discerning listeners may feel that ANC-equipped headphones focus on negating background noise to the detriment of their ability to enhance the music-listening experience — sometimes resulting in a cheaper pair of standard headphones offering a more enjoyable audio performance.
As with much else in the world of music audio, technology advances at great speed, and consumers planning to buy would be well advised to decide exactly what they expect from a headphone set offering active noise control. Prior to purchase, it would be wise to compare and contrast possible purchase options on the basis of a comparative listening test, which should also include an equivalent standard headphone set.
Images by Carbon NYC and Brooke Hoyer, used under Creative Commons license
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