Ambient sound-based proximity detection with smartphones

This paper presents a system design and experimental evaluations for ambient sound-based proximity detection with smartphones. Ambient sound is useful as spatiotemporal identifier. This is because ambient sound contains abundant information which depends on time and space. To detect proximity at high accuracy, we calculate cross correlation in frequency domain for the similarity measure of ambient sound. The results of experiments show that our system discriminates 5 rooms with the accuracy of true positive 94.9% and false positive 0.1%.