: How do active noise-cancelling headphones work? :.

Audio-Technica's QuietPoint® headphones use active noise-cancelling technology to reduce distracting background noise, providing an exceptionally comfortable and restful listening environment in areas with high ambient noise. Active noise-cancelling headphones have components not present in ordinary headphones:
 

• Microphone – Noise-cancelling headphones feature a miniature microphone in the earpiece that picks up ambient noise (such as traffic, air-handling systems, etc.)
  
   
• Noise-canceling circuitry – Electronics in the ear piece create a noise-cancelling wave that is 180° out of phase with the ambient noise. This wave acts like a noise eraser: it cancels out the annoying sounds that surround you without diminishing the audio you want to hear. The result…a peaceful enclave to enjoy the music or movies of your choice.
  
   
• Battery – The noise-cancelling electronics are battery-powered.

Ideal for use with MP3, CD, DVD & in-flight entertainment systems, ATH-ANC7b QuietPoint® closed-back headphones deliver clear, high-resolution sound, with impactful bass, a detailed midrange, extended treble and accurate imaging in an immersive soundfield. Their earcups have been redesigned for greater comfort, with generously cushioned padding and a shape that fits easily over any ear.

The ATH-ANC7b QuietPoint® headphones feature large-aperture 40 mm drivers with neodymium magnet systems and extremely high 109dB sensitivity to provide generous volume levels from any music source. The headphones also work when the noise-cancelling function is turned off, and operate in passive mode without batteries. Noise-cancelling electronics are fully integrated in each earpiece, with no need for external modules.

• ATH-ANC7b QuietPoint® noise-cancelling headphones feature ANC circuitry that effectively reduces environmental noise by up to 85%
• Lightweight, compact, fold-flat design is ideal for travel
• Ideal for use with Apple® iPod®, iPhone™ and iPod touch® portable music and DVD players, laptop computers, in-flight entertainment systems and other devices
• Closed-back headphones feature large-aperture 40 mm drivers with neodymium magnet systems for impactful bass, extended treble and higher fidelity
• Comfortable earcups with generously cushioned padding and a shape that fits easily over any ear
• Audio functions (in passive mode) even without the battery
• Fully integrated electronics—no external modules needed
• Fold-flat design with included 3.5 mm mini-plugs, a full-size ¼” adapter, a specialized airline adapter for connecting to in-flight entertainment systems, and a handy carrying case