A headset can be used to listen to music or other audio programming and can also be used conduct a telephone conversation. A microphone on a biased arm pivots between an extended position and a retracted position so as to be in place for conducting a telephone call, but out of the way when not in use....http://www.google.com.hk/patents/US20020067825?utm_source=gb-gplus-share專利 US20020067825 - INTEGRATED HEADPHONES FOR AUDIO PROGRAMMING AND WIRELESS COMMUNICATIONS WITH A BIASED MICROPHONE BOOM AND METHOD OF IMPLEMENTING SAME
