The method includes: selecting {TAIL ~ a first combination} of transmission elements from among multiple transmission elements, wherein the first combination of transmission elements includes at least two transmission elements adjacent to each other; and vibrating the transmission surfaces of the first combination of transmission elements in a substantially same phase to transmit the ultrasonic wave with {HEAD ~ a first directivity} 
The method includes : selecting { TAIL ~ a first combination } of transmission elements from among multiple transmission elements , wherein the first combination of transmission elements includes at least two transmission elements adjacent to each other ; and vibrating the transmission surfaces of the first combination of transmission elements in a substantially same phase to transmit the ultrasonic wave with { HEAD ~ a first directivity }
OTH OTH OTH OTH OTH 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD