This is a simulation for bats emit sound waves to find objects (butterfly).
You can drag both bat/butterfly , then click play.

translate strings in simulation to different language format before download
Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
Download EJS jar file(1437.5kB):double click downloaded file to run it. (8 times by 8 users) , Download EJS source View EJS source