Noise cancellation makes it possible to enjoy music or hear important information without volume raising excessively. Noise cancelling headsets increase the signal-to-noise ratio significantly more than passive noise attenuating headsets or no headsets, making hearing important information such as safety announcements easier. It helps a passenger sleep in a noisy vehicle and an airliner. Noise-cancelling headsets can improve listening enough to completely offset the effect of a distracting concurrent activity.
Noise-cancelling headsets use active noise control to cancel the lower-frequency portions of the noise; they depend on more traditional methods such as soundproofing to prevent higher-frequency noise from reaching the ear. This approach is preferred because it reduces the demand for complicated electronic circuitry that would be required for noise cancellation at higher frequencies, where active cancellation is less effective. To truly cancel high frequency components (coming at the ear from all directions), the sensor and emitter for the cancelling waveform would have to be adjacent to the user’s eardrum, which is not currently technically feasible.
By the 1950s, systems were created to cancel the noise in helicopter and airplane cockpits. Noise-cancelling aviation headsets are now commonly available.
Currently, most noise-cancelling headsets use analogue technology. This is in contrast to other forms of active noise and vibration control in which digital processing is the standard method.
A number of airlines provide noise-cancelling headsets in their business and first class cabins. Noise cancelling is particularly effective against airplane engine noise. In these cases, the headsets are about the same size as normal headsets. The electronics, located in the plane handset, take the sound from the microphone behind the headset, invert it, and add it back into the audio signal, which reduces background noise.
Circumaural headsets enclose the wearer’s ear completely. This provides passive noise isolation so that electronic noise cancellation circuitry can perform better.
Noise-cancelling headsets can reduce extraneous noise significantly, but have some limitations (depending on model):
They are more expensive than regular headsets.
They consume power, usually supplied by a USB port or a battery that must occasionally be replaced or recharged. Without power, some models are unable even to function as regular headsets.
The noise-cancelling circuitry required for them to operate may reduce audio quality and introduce some high-frequency hiss. However this limitation may be offset by reductions in external noises that would otherwise reduce audio quality.
Models can be bulkier and/or heavier than regular headsets to incorporate batteries and electronics.
They may make some individuals queasy.
Publish Date: October 3, 2014 4:00 AM