国外的發明家們正继续探究着一些测定大型水輪机水流的新方法。美国所提出的音响方法是这些方法中的一种。我們可以很容易地想像出这种音响方法的实質。众所週知的事实:一个立定的观察者倾听着迅速驶近 Foreign inventors are continuing to explore new ways to measure the flow of large turbines. The acoustics method proposed by the United States is one of these methods. We can easily imagine the essence of this sound method. It is a well-known fact that an established observer listens to approaching quickly