Determining the speed of sound with stereo head-phones

摘要

In this example we describe how the speed of sound can be determined using simple stereo headphones (ear buds) and sound analysis freeware. When watching the start of a race from a distance of sever-al hundred meters, one notices a time difference Δt between the visual perception of the start signal and hearing the bang. Sound is therefore not propagated instantaneously, but at a finite speed c. There are numerous other examples in the daily lives of pupils that support this conclusion. For instance, the observed time difference between the perception of thunder and lightning is a particularly impressive example that enables us to calculate how far away a storm is.