Then {HEAD ~ an analysis} on the states of the M last 20ms blocks allows the final decision on {TAIL ~ voice presence} 
Then { HEAD ~ an analysis } on the states of the M last 20ms blocks allows the final decision on { TAIL ~ voice presence }
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL