{TAIL ~ Calibration} of the system is provided by means for an operator to specify tone densities for {HEAD ~ the second medium} that correlate to signal levels derived from the first medium for each channel 
{ TAIL ~ Calibration } of the system is provided by means for an operator to specify tone densities for { HEAD ~ the second medium } that correlate to signal levels derived from the first medium for each channel
TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH