驻波法测量声速实验的讨论

根据声波在2个换能器之间多次反射和声波在空气中的衰减,研究了驻波法测量声速实验中接收器输出信号随接收器到发送器间距离的变化.理论推导结果表明:声波在一般情况下不是严格的驻波,但是当反射比接近-1时则是双曲函数形式的驻波,这与实验测量结果一致.只有接收器到发送器的距离比较远,反射比接近-1时,才能得到几乎理想的驻波.

Discussion on the experiment of sound velocity measured by standing wave method

From sound multi-reflection between two ultrasonic transducers and the sound attenuation in air, the article researches the variation of signal output of receiver with distance between receiver and emitter in the experiment of sound velocity measured by standing wave method. A formula of the sound wave acted on the receiver is deduced from the research. The sound wave generally is not a standing wave, but a hyperbolic standing wave. Only when the distance between receiver and emitter is long enough and the reflectance equals to -1, the sound wave turns to be an almost perfect standing wave, which is consistent with the experimental results.