{TAIL ~ A detection area} of {HEAD ~ an ultrasonic wave} depends on an area of a transmission surface and corresponding characteristic length of the transmission surface 
{ TAIL ~ A detection area } of { HEAD ~ an ultrasonic wave } depends on an area of a transmission surface and corresponding characteristic length of the transmission surface
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH