A diffraction grating is a spatial filter causing sound waves or optical waves to reflect in dire... more A diffraction grating is a spatial filter causing sound waves or optical waves to reflect in directions determined by the frequency of the waves and the period of the grating. The classical grating equation is the governing principle that has successfully described the diffraction phenomena caused by gratings. However, in this work, we show experimental observation of the so-called sub-harmonic diffraction in acoustics that cannot be explained by the classical grating equation. Experiments indicate two physical phenomena causing the effect: internal scattering effects within the corrugation causing a phase shift and nonlinear acoustic effects generating new frequencies. This discovery expands our current understanding of the diffraction phenomenon, and it also makes it possible to better design spatial diffraction spectra, such as a rainbow effect in optics with a more complicated color spectrum than a traditional rainbow. The discovery reveals also a possibly new technique to study nonlinear acoustics by exploitation of the natural spatial filtering effect inherent to an acoustic diffraction grating.
Journal of the Acoustical Society of America, May 1, 2007
Hellenistic theaters are well known for their marvelous acoustics. A numerical study reveals that... more Hellenistic theaters are well known for their marvelous acoustics. A numerical study reveals that the seat rows of the theater unexpectedly play an essential role in the acoustics, at least when the theater is not fully filled with spectators. The seats, which constitute a corrugated surface, serve as an acoustic filter that passes sound coming from the stage at the expense of surrounding acoustic noise. Whether a coincidence or not, the famous theater of Epidaurus was built with optimized shape and dimensions.
... Acknowledgement Nico F. Declercq is a postdoctoral fellow of the Fund for Scientific Research... more ... Acknowledgement Nico F. Declercq is a postdoctoral fellow of the Fund for Scientific Research - Flanders (FWO - Vlaanderen). References ... IEEE-trans. on UFFC 52 (2005) 776791. [2] M. Hayes: Inhomogeneous plane waves. Arch. Ration. Mech. Anal. 85 (1984) 4179. ...
Journal of the Acoustical Society of America, Oct 1, 2022
The acoustics education program at the Georgia Institute of Technology (Georgia Tech) is run by m... more The acoustics education program at the Georgia Institute of Technology (Georgia Tech) is run by members of the Acoustics and Dynamics research area group from the School of Mechanical Engineering. We will briefly review the scope of this program in terms of education and research activities
A diffraction grating is a spatial filter causing sound waves or optical waves to reflect in dire... more A diffraction grating is a spatial filter causing sound waves or optical waves to reflect in directions determined by the frequency of the waves and the period of the grating. The classical grating equation is the governing principle that has successfully described the diffraction phenomena caused by gratings. However, in this work, we show experimental observation of the so-called sub-harmonic diffraction in acoustics that cannot be explained by the classical grating equation. Experiments indicate two physical phenomena causing the effect: internal scattering effects within the corrugation causing a phase shift and nonlinear acoustic effects generating new frequencies. This discovery expands our current understanding of the diffraction phenomenon, and it also makes it possible to better design spatial diffraction spectra, such as a rainbow effect in optics with a more complicated color spectrum than a traditional rainbow. The discovery reveals also a possibly new technique to study nonlinear acoustics by exploitation of the natural spatial filtering effect inherent to an acoustic diffraction grating.
Journal of the Acoustical Society of America, May 1, 2007
Hellenistic theaters are well known for their marvelous acoustics. A numerical study reveals that... more Hellenistic theaters are well known for their marvelous acoustics. A numerical study reveals that the seat rows of the theater unexpectedly play an essential role in the acoustics, at least when the theater is not fully filled with spectators. The seats, which constitute a corrugated surface, serve as an acoustic filter that passes sound coming from the stage at the expense of surrounding acoustic noise. Whether a coincidence or not, the famous theater of Epidaurus was built with optimized shape and dimensions.
... Acknowledgement Nico F. Declercq is a postdoctoral fellow of the Fund for Scientific Research... more ... Acknowledgement Nico F. Declercq is a postdoctoral fellow of the Fund for Scientific Research - Flanders (FWO - Vlaanderen). References ... IEEE-trans. on UFFC 52 (2005) 776791. [2] M. Hayes: Inhomogeneous plane waves. Arch. Ration. Mech. Anal. 85 (1984) 4179. ...
Journal of the Acoustical Society of America, Oct 1, 2022
The acoustics education program at the Georgia Institute of Technology (Georgia Tech) is run by m... more The acoustics education program at the Georgia Institute of Technology (Georgia Tech) is run by members of the Acoustics and Dynamics research area group from the School of Mechanical Engineering. We will briefly review the scope of this program in terms of education and research activities
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Papers by Nico F. Declercq