Abstract: A new explanation of the experiment to measure the speed of sound in the air is proposed. It is shown that the sound pressure is the result of the superposition of infinite reflections of sound waves between the transmitting end and the receiving end. After considering the energy dissipation in the air as well as reflected energy loss and half-wave loss on the two transducer ends, the relationship between the pressure and the displacement of sound waves at the receiving end is obtained. We can reasonably get the law of the sound pressure signal varies with the distance between two transducer ends, which conforms to the concrete experiment.

Key words: sound speed measurement, sound pressure, superposition of infinite reflections, amplitude decay, half-wave loss