Authors: Jurij Prezelj, Luka Čurovič, Tadej Novakovič, Jure Murovec
Abstract: With the introduction of the sub-windowing approach to beamforming in time domain, the temporal resolution of the beamforming can be defined by the propagation time of sound over the microphones. During this time, within the sub-window, the direction of the dominant sound source can be detected by using only a microphone pair, for each spatial axis. Sub-windowing of the microphone signals into time intervals shorter than one millisecond allows a statistical analysis of the immission directivity during the typically used 125 msec window. Using a differential microphone array, it is possible to shorten the length of the sub-window for detection of direction to less than 0.24 msec, providing 520 results of dominant direction, during an integration performed according to the “fast” time constant. Hypothesis is proposed, that by attributing the temporal dominant direction to the temporal sound pressure level within the sub-window, and by integrating the results, the immission directivity can be obtained. Hypothesis is devised from the insight of the chaotic/fractal property of the environmental noise. Numerical simulations, experiments, and practical application of the algorithm, based on the proposed hypothesis, provide promising results.
Assessment of immission directivity, as noise compass
Keywords: Beamforming, immission directivity, noise compass, microphone array, environmental noise