an analog to {HEAD ~ digital converter} that converts an analog acoustic input signal into {TAIL ~ a digital input signal} 
an analog to { HEAD ~ digital converter } that converts an analog acoustic input signal into { TAIL ~ a digital input signal }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL