echo technique

例句：

1. 1. The echo technique is used to measure the speed of sound in water.
   回声技术用于测量水中声速。
2. 2.The echo technique was developed by scientists to study underwater sounds.
   回声技术是由科学家开发来研究水下声音的。
3. 3. In echo technology, the sound waves are reflected off a surface and then recorded.
   在回声技术中，声波被反射到表面后被记录下来。