Investigation of Acoustic Quantities in a School Environment Using a Smartphone and the Phyphox Application

Abstract

Smartphones with built-in sensors are increasingly used as auxiliary measuring devices in science education. This paper presents a didactic application of a smartphone and the Phyphox application for investigating acoustic quantities in a school environment. Two experiments were carried out: the determination of the speed of sound in air using the reflection method with the Sonar tool, and the analysis of the relative decrease in uncalibrated sound pressure level as a function of distance from the sound source. The measurements were performed using an iPhone 14 Pro running iOS 26.2, and the data were processed in MS Excel. At an air temperature of , the speed of sound obtained from linear regression was , which agrees well with the theoretical value of . In the second experiment, a Dyson Cyclone V10 vacuum cleaner operating at its lowest power setting was used as the sound source. Since the Phyphox readings were not compared with a calibrated sound level meter, they were used only for relative analysis. In the indoor setting, a classroom measuring approximately 5.0 m × 4.6 m × 2.7 m, a slope of approximately  per decade was obtained, whereas outdoors the slope was  per decade. The results show that room conditions, reflections, microphone orientation, and the lack of device calibration significantly affect the measurements.