As surrounding noise is captured by the microphone, the electronic circuitry generates a signal of the opposite phase which causes destructive interference to occur, that is to say, a sound wave is generated with opposite amplitude and the signals cancel. The sound with the reversed phase is emitted by the driver and cancels out the noise as it enters the ear. Noise is kept low at the ear, making it possible to enjoy music without raising the volume unnecessarily These headphones are designed to attenuate low frequency inconsonant noise of 1,500 Hz or less. They do not have great effect on relatively high frequency components such as automobile horns, telephone rings or the human voice. PRODUCT FEATURES: Cancels ambient noise; Designed for in-flight use; Travel-fold design for easy carrying; 2 level noise canceling effect; Separate controller; Plug adaptor for aircraft included; Frequency response 10Hz-22kHz; Long battery life - up to 50hrs. Minimize