Comparative Study of Passive and Active Acoustic Sensing for Indoor Room Recognition

Abstract

The ability to accurately determine the location within indoor settings is crucial for various applications such as indoor navigation, interactive floor plans, and room-specific services. While GPS technology has revolutionized outdoor positioning, it falls short in providing precise location information within buildings due to signal blockage. To address this limitation, specialized indoor positioning systems utilizing acoustic sensing have been explored, leveraging deep learning models. This paper presents a comparative study of passive and active acoustic sensing systems for room recognition. Passive sensing involves capturing existing background noise in a room and using it as an identifier, while active sensing emits acoustic signals and analyzes the resulting echoes. Previous research has primarily focused on active sensing, achieving high classification accuracy but facing challenges related to device orientation and the presence of multiple individuals. Moreover, the emission of high-frequency chirps used in active sensing may cause discomfort to pets. The results indicate that passive sensing achieves an accuracy of 73.7%, slightly outperforming active sensing at 63.5% in baseline conditions. However, in the presence of constant background noise, passive sensing accuracy drops to 21.7%, while active sensing exhibits better resilience with an accuracy of 59.7%. Furthermore, when the device orientation is altered by 90 degrees, active sensing results in a lower in accuracy (45.5%), while passive sensing maintains better performance at 71%. The impact of multiple individuals in the room had a relatively minor effect on passive sensing systems, achieving an accuracy of 72.2%. Active sensing was shown to be not as resilient, reaching an accuracy of 44.2%.