Sound waves in a tube: measuring sound pressure profiles using smartphones

Abstract

Abstract We present an experiment designed to study standing waves in a tube with one closed end. Two smartphones are used, one to emit a sound signal with a chosen frequency and another equipped with a microphone to detect the sound pressure level inside the tube. Due to the finite diameter of the tube, the standing wave node (or antinode) appears slightly outside of its opened end so the end correction is applied. Results show a good agreement with the theory, making this proposal suitable to be applied to secondary school classes. It is a low cost experiment and has the potential to increase the understanding of this physical phenomenon by secondary students.