first summing amplifier means for generating a left right summing output signal which is {HEAD ~ a function} of {TAIL ~ the sum} of said left and right output pulses 
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first summing amplifier means for generating a left right summing output signal which is { HEAD ~ a function } of { TAIL ~ the sum } of said left and right output pulses
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH