Such signals may thus demonstrate {HEAD ~ a relationship} between the pressure signal 302 and {TAIL ~ the density signal} 304, as those signals change over time 
Such signals may thus demonstrate { HEAD ~ a relationship } between the pressure signal 302 and { TAIL ~ the density signal } 304 , as those signals change over time
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH