Coefficient of restitution (COR) is a measure of elasticity of collision between two bodies. This article presents a method for measurement of the coefficient of restitution between bouncing a rubber ball and a hard surface. Each impact makes a sound which is detected by a microphone connected to computer's sound card and the recorded sound is analysed. Coefficient of restitution is calculated from the delays between each two consecutive impacts. Programs listed and commented in the article utilises Python with the python‑alsaaudio library for sound recording, !Scipy for data processing and matplotlib for waveform visualisation. It runs under the Linux operating system and a whole experiment is meant primarily for students and education purposes.