A device for performing {HEAD ~ electroacoustic functions} including noise cancellation, {TAIL ~ communication interface}, and headphone functions 
A device for performing { HEAD ~ electroacoustic functions } including noise cancellation , { TAIL ~ communication interface } , and headphone functions
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH