71 headset usb headset design over ear types closed dynamic transmission mode cable types of connection usb usb 20 type of cable single sided length of cable 27 m sound modes 71 hardware surround headset type of headphones headband features adjustable headband padded headband function mute headphone impedance 32 ohm driver 40 mm microphone properties noise cancelling microphone microphone frequency range 20 20000 hz microphone sensitivity