  In this work, a new Physics laboratory experiment on Acoustics beats is
presented. We have designed a simple experimental setup to study superposition
of sound waves of slightly different frequencies (acoustic beat). The
microphone of a smartphone is used to capture the sound waves emitted by two
equidistant speakers from the mobile which are at the same time connected to
two AC generators. The smartphone is used as a measuring instrument. By means
of a simple and free AndroidTM application, the sound level (in dB) as a
function of time is measured and exported to a .csv format file. Applying
common graphing analysis and a fitting procedure, the frequency of the beat is
obtained. The beat frequencies as obtained from the smartphone data are
compared with the difference of the frequencies set at the AC generator. A very
good agreement is obtained being the percentage discrepancies within 1 %.
