Most in-ear headphones rely on passive noise isolation to keep unwanted sounds from ruining your listening experience. Now Bose is taking things a step farther. Using active noise cancelling technology, the Bose QuietComfort 20 Acoustic Noise Cancelling headphones let you listen to unblemished audio in even the noisiest of environments. To do so, they rely on two tiny microphones per ear — one on the inside of the earphone, one on the outside — to identify ambient sounds, compare them to what you're listening to using advanced digital signal processing, and produce an opposite signal to cancel them out. When combined with TriPort technology, Active EQ and secure StayHear+ tips, you get a listening experience that simply can't be matched by normal headphones.