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