Noise Cancellation vs. Noise Isolation
Noise-cancelling headphones reduce unwanted ambient sounds (i.e., acoustic noise) by means of active noise control (ANC). This involves using one or more microphones placed near the ear, and electronic circuitry which uses the microphone signal to generate an "antinoise" signal. When the antinoise signal is produced by the speaker driver in the headphone, destructive interference cancels out the ambient noise as heard within the enclosed volume of the headphone. They should not be confused with noise isolating headphones.
Noise cancellation makes it possible to enjoy music without raising the volume excessively. It can also help a passenger sleep in a noisy vehicle such as an airliner. Research examining the benefits of noise cancelling headphones in the aviation environment has found that compared to passive noise attenuating headphones or no headphones, noise cancelling headphones significantly increases the signal to noise ratio, making hearing important information such as safety announcements easier. The benefits of noise cancelling headphones also extend to situations involving concurrent task (dual task) performance such as completing a math based task (e.g., Sudoku) as well as listening task.
Noise-cancelling headphones typically use ANC to cancel the lower-frequency portions of the noise; they depend on more traditional methods such assoundproofing 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 technically feasible.
Noise isolating headphones keep the audio inside your ear and the noise outside by physically impeding exterior noise from reaching the ear canal; resulting in an extremely portable listening experience and does not require heavy battery-powered technology (noise-cancelling headphones do require) to actively invert environmental sounds. For both in ear and over ear headphone designs, noise isolation works by combining the insulating properties of clever design and a comfortable fit to block disruptive ambient noise.
For over-ear headphone designs, effective noise-isolation relies upon the angle and pressure with which the earcups sit on the ear. Earcups that sit too tight to the ear are uncomfortable and discourage longer listening sessions; earcups that sit too loose on the ear produce muddled sound and allow extensive sound leakage. Adjusting to the user’s movements and perfectly accommodating their profile means that nothing can interfere with a crystal clear listening experience.
In-ear earphones generate noise isolation by the forming of a barrier within the ear canal to block ambient noise. Most in-ear earphones offer small, medium and large sizes of ear-tip to ensure that every individual can find a comfortable fit and achieve excellent noise isolation. The eartips\' soft silicone exterior provides a comfortable secure fit and keeps external noise out, while the firmer silicone interior produces a tight seal to the aluminium body of the earphone itself to prevent leakage as sound is channelled into the ear.
When done well, noise isolation allows you to enjoy a secluded listening experience that delivers accurate sound representation across the full audio spectrum.