The second input transducer supplies {HEAD ~ an electrical signal} corresponding to the residual noise to the control circuitry to cancel {TAIL ~ the residual noise} 
The second input transducer supplies { HEAD ~ an electrical signal } corresponding to the residual noise to the control circuitry to cancel { TAIL ~ the residual noise }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL