When {HEAD ~ the first number} of shock events exceeds {TAIL ~ an upper event threshold}, a control signal is adjusted in order to adjust a frequency spectrum of noise affecting the shock detector 
exceeds
When { HEAD ~ the first number } of shock events exceeds { TAIL ~ an upper event threshold } , a control signal is adjusted in order to adjust a frequency spectrum of noise affecting the shock detector
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH