Recently released this summer, the Headphones 700 are the best wireless over-ear headphones that Bose has to over. The combine the best-in-class noise-cancellation with great audio quality. Other than the design overhaul, the biggest difference from the QuietComfort 35 II is that the Headphones 700 have a significantly upgraded microphone array. This allows the headphones to have a wonderful tranparancy mode (or ambient listening mode), and makes maybe the best headphones you can buy for call quality.
These early headphones used moving iron drivers, with either single-ended or balanced armatures. The common single-ended type used voice coils wound around the poles of a permanent magnet, which were positioned close to a flexible steel diaphragm. The audio current through the coils varied the magnetic field of the magnet, exerting a varying force on the diaphragm, causing it to vibrate, creating sound waves. The requirement for high sensitivity meant that no damping was used, so the frequency response of the diaphragm had large peaks due to resonance, resulting in poor sound quality. These early models lacked padding, and were often uncomfortable to wear for long periods. Their impedance varied; headphones used in telegraph and telephone work had an impedance of 75 ohms. Those used with early wireless radio had more turns of finer wire to increase sensitivity. Impedance of 1000 to 2000 ohms was common, which suited both crystal sets and triode receivers. Some very sensitive headphones, such as those manufactured by Brandes around 1919, were commonly used for early radio work.
These headphones hush ambient noise by creating anti-noise that obviates the noise at your ear. They don't eliminate the outside world, but the better models significantly reduce the whoosh of airplanes' air-conditioning systems. Noise-canceling headphones come in all forms, from full-size to earbuds. Since you no longer have to crank up the volume to overcome background noise, this type of headphone lets you listen at lower levels, which leads to reduced ear fatigue. You'll also hear more low-level detail in your music.
Although some headphones available are wired, many more are available that are wireless, and use Bluetooth to enable your music to be heard, even if the stereo or other device is several feet or even a few rooms away. Wired headphones deliver superior sound quality to wireless and Bluetooth because there's no chance of picking up interference from other devices, which sometimes happens with wireless headphones. In addition, wired headphones have no batteries to power them, so there's no chance of interruption should the batteries wear out.