Sony Fontopia MDR-NC11A

Sony Fontopia MDR-NC11A ... 9mm driver units produce powerful sound for your listening enjoyment. So tune out noise at work, when you travel, or even when you are trying to sleep in a loud environment. The Noise Canceling circuit actually senses outside noise with built-in microphones and sends an equal-but-opposite canceling signal to the headphones. The Noise Canceling on/off switch located on the battery box indicates when Noise Canceling is operating. Additional features include the Fontopia in-the-ear design, Volume control, and a Miniature connection box for a battery. Silence outside sound with Sony.