Geo-referenced sound data are often used in the field of acoustics education to learn about the urban acoustic environment. Simple soundwalks and sound collections are also employed, in which acquiring additional information such as visual data, recorded sound data, and GPS location data are helpful to produce a map with sound data and sound collection and to carry out more profound discussions in educational activities. In order to enrich these acoustic educational and environmental survey activities with a simple tool, the use of multifunctional sound-pressure level (SPL) measurement applications with mobile devices are proposed. Some experiences of combined activities of the above methods using the applications and mobile devices are reported in this paper. In this study, applications for SPL measurements, which record GPS location data, sound, photo, and video during measurements, were used to produce geo-referenced sound data. First, the accuracy of the applications was checked and we found them to have reasonable accuracy when used with iOS devices; for example, the averaged error was less than 1.5 dB(A) with iPhone XS. Next, they were actually used in a simple soundwalk-like field survey and the resulting geo-referenced sound data were presented to discuss the merits and demerits of each application. Overall, the applications used in this work were found to be useful; for example, recorded sound allowed us to check the main sound source and to carry out discussions using collected sound samples later, and photos and videos allowed us to grasp the impressions and situations around the measuring points. Therefore, these multifunctional sound level meter (SLM) applications can be effectively used for various purposes, including acoustics education for learning about urban acoustic environments.
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