Undertaking long-term acoustic measurements on sites located near an airport is related to a problem of large quantities of recorded data which very often represents information not related to flight operations. In such areas, usually defined as zones of limited use, other sources of noise often exist such as roads or railway lines treated in such context as an acoustic background. Manual verification of such recorded data is a costly and time-consuming process. Automatic differentiation of the tested noise source from background and precise recognition of quantitative impact of aircraft noise on the acoustic climate in a particular area is an important task. This paper presents the idea of a method that can be used for identifying aircraft operations (flights, take-offs, landings) supported by experimental studies carried out with the use of 3D Microflown sound intensity probe and SoundField ST350 ambisonic microphone. The proposed method is based on determining the spatial sound intensity vector in the tested acoustic field during a monitoring timespan. On the grounds of this information, aircraft operations are marked in a continuous record of noise events.
The paper presents results of determination of sound wave direction based on signals from first-order ambisonic microphone. The experiment consisted in recording the test signals with the SoundField microphone positioned in the axis of the turntable in the anechoic chamber. The spherical coordinates of the sound intensity vector were calculated with use of three different conceptual and numerical approaches and were compared to actual values resulting from the geometry of the system. Accuracy of the localization of the sound source depending on the frequencies and the method for determination of the spherical coordinates as well as on the time constant and the parameters of the signal recording was presented. The obtained results show the effectiveness of the calculation methods used for localization of the sound source.
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