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