Noise cancellation is a feature that reduces or eliminates unwanted background or ambient sounds. This can improve the sound quality when listening to music or talking. There are two main types of noise cancellation: passive and active. Passive noise cancellation uses physical barriers, such as the tight fit of the headphones on the ears, to block out ambient sound. Active Noise Cancellation (ANC) uses electronics to create sound that "cancels out" unwanted sounds.