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