The Smartphone as a Sound Level Meter: Visualizing Acoustical Beats

Abstract

[EN] Acoustics is a topic in first year Physics courses for engineering students. In this respect, we present in this work a simple experiment to study acoustic beat phenomenon. The superposition of sound waves of slightly different frequencies is captured with the microphone of a smartphone which is placed equidistantly from two speakers which are connected at the same time to AC generators. The smartphone is used here as a measuring instrument. Data registered from the sound level versus time were collected and exported to a «.csv» file for further analysis by means of a free Android application. Based on these data and applying a simple graphing analysis the frequency of the beat was determined and compared with the frequency difference set at the AC generators. Percentage discrepancies within 1% were obtained. This indicates the efficacy of the method used.