{HEAD ~ A subtracter} subtracts {TAIL ~ the estimated wraparound speech signal ai d′} from the input speech signal “bi” to generate an echo cancellation signal “ei” 
subtracts
{ HEAD ~ A subtracter } subtracts { TAIL ~ the estimated wraparound speech signal ai d′ } from the input speech signal “ bi ” to generate an echo cancellation signal “ ei ”
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH