The mystery of the “Maoshan Bugle,” first classified in 1997, involves the surprising production of clearly audible bugle-like sounds in response to a launched firecracker blast in the square in front of the Southern Jiangsu Victory Monument in Jiangsu, China. In this paper, we analyze the origin of these sounds, attributing them to interference due to six groups of stairs leading to a monument in the square. Our analysis indicates that the stairs act as a reflection grating for the sounds produced by a firecracker blast. Based on Kirchhoff's diffraction formula, we calculate the spectra and the fundamental frequencies of the bugle-like echoes using the parameters of the actual structures. The calculated spectra fits well with the experimental results derived from the audio samples recorded on site.

Topics
Acoustic noise, Speed of sound, Acoustic phenomena, Spectrograms, Acoustic waves, Fourier analysis, Diffraction theory, Kirchhoff's diffraction formula, Educational assessment, News and events
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© 2014 American Association of Physics Teachers.
2014
American Association of Physics Teachers

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