echolocation
noun [ U ] uk/ˌek.əʊ.ləʊˈkeɪ.ʃən/ us/ˌek.oʊ.loʊˈkeɪ.ʃən/
（蝙蝠等动物的）回声定位
a process in which animals, for example bats (= small animals with wings that fly at night), find their way in the dark by producing sound waves that echo (= are heard again) when they are reflected off an object
Dolphins locate underwater creatures using echolocation. 海豚利用回声定位来确定水下生物的位置。