Sound of a nut rolling inside an elastic rubber balloon

Abstract

This article studies the sound produced by nuts of different shapes swirling in an elastic rubber balloon. First, the sound is studied experimentally, both in terms of frequency and amplitude. Regarding the frequency components of the sound, we show that they can be divided into two main contributions – one due to the oscillations of the elastic membrane, the other due to the hits of the nut against the balloon – and present models to describe the frequency’s dependence on the main parameters of the system. We analysed the influence of several parameters such as the balloon’s geometry, the nut’s geometry and its mass.