People have always wanted more from headphones: more volume, more dependability, more fidelity, and, finally, more portability as wireless sound has become more common. But lately, it’s all about what headphones can provide you with less of. Of course, we’re talking about noise. It’s no longer enough for headphones to produce good sound, thanks to noise-cancelling technology. Headphones are now desirable because they can detect and suppress ambient sound from the world around them. The feature has become so common that headphone manufacturers brag about the various types of noise-cancelling technology they employ. Some are proprietary, and they are not all created equal. It’s useful to understand how noise-cancelling earbuds and headphones work before purchasing the best noise-cancelling products. The first method is known as passive noise cancellation, and it is used by any earphone set. The concept of passive noise cancellation is straightforward: a physical barrier blocks out noise. This is, of course, a low-tech method, but depending on the materials used, it can be quite effective. With the tight seal that the ear cushions create, well-designed headphones can create a nice “cocoon” of silence. However, this does not always work in noisy environments, which is where active noise cancellation (ANC) comes in. Sound, of course, travels in waves, and the frequency of the waves determines whether you hear high or low frequencies. Active noise-cancelling headphones use an extra microphone to pick up outside sound and direct it to your ears. Then they use additional, dedicated speakers to generate their own sound wave. This wave is an inverted mirror image of the original wave, with “peaks” and “valleys” of the same depth counteracting its frequency. This effectively cancels out the incoming noise, resulting in essentially silence reaching your headphones.
