Smartphone-based sound level measurement apps: Evaluation of directional response

Abstract

Smartphones have evolved into powerful devices with computing capabilities that rival the power of personal computers. Any smartphone can now be turned into a sound-measuring device because of its built-in microphone. Many sound measuring apps exist on the market for various mobile platforms. In our earlier research, we showed that a smart device with an adequate app can achieve compliance with most of the Class 2 requirements for periodic testing. In this paper, we present the methods and results of measuring directional response of a sound level meter consisting of a smartphone and one commercially available sound level meter app in the horizontal plane. We used both the built-in smartphone microphone and an external microphone according to relevant IEC [International Electrotechnical Commission] and ANSI [American National Standards Institute] sound level meter standards. The results show that the sound level meter app and an external microphone can achieve compliance with the requirements for Class 2 of IEC 61672/ANSI S1.4–2014 standard in the horizontal plane.