An encoder converts the digital data into {TAIL ~ audio tones} that synthesize frequency characteristics of {HEAD ~ human speech} 
An encoder converts the digital data into { TAIL ~ audio tones } that synthesize frequency characteristics of { HEAD ~ human speech }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD