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Published on: August 2, 2016
Experimental and quantitative evaluation of frequency modulation caused by Doppler effect around high-speed moving
Mariko Akutsu1,2, Toki Uda1, Yasuhiro Oikawa2
1Environmental Engineering Division, Railway Technical Research Institute, Kokubunji-shi, Tokyo 185-8540, Japan.
Abstract:
High-speed train noise remains a wayside environmental issue. For accurate noise prediction, the characteristics of a moving sound source must be revealed. In this work, the frequency modulation of sound waves emitted from a high-speed moving sound source was experimentally investigated. In the experiment, the sound field around a running train model emitting a 40 kHz pure tone was measured by an optical measurement technique, parallel phase-shifting interferometry, which can visualize instantaneous sound fields. For quantitative evaluation, a lens distortion correction was also developed and adopted for the visualization results. From the measured result of a sound source moving at a running speed of 280 km/h, the frequency modulation, known as the Doppler effect, was observed, and the measured frequency agreed well with the theoretical values.
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