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Updated: Aug 11, 2026
10:35
Using Microwave and Macroscopic Samples of Dielectric Solids to Study the Photonic Properties of Disordered Photonic Bandgap Materials
Published on: September 26, 2014
Anomalous Doppler effects in phononic band gaps
Xinhua Hu1, Zhihong Hang, Jensen Li
1Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|February 21, 2006
Summary
Acoustic Doppler effects in periodic media were analyzed. Moving sources can generate audible sound within band gaps, unlike stationary sources, with unusual Doppler shifts.
Area of Science:
- Acoustics
- Wave Propagation
- Solid State Physics
Background:
- Periodic acoustic media exhibit unique wave propagation properties, including band gaps where sound transmission is forbidden.
- The Doppler effect typically describes frequency shifts due to relative motion between a source and observer.
Purpose of the Study:
- To investigate the theoretical and experimental aspects of Doppler effects in periodic acoustic media.
- To understand sound detectability within band gaps for both stationary and moving sources.
Main Methods:
- Derivation of analytical formulas using the Green's function formalism.
- Theoretical analysis of wave propagation in periodic structures.
- Experimental validation of theoretical predictions.
Main Results:
- A stationary source inside a band gap is inaudible to a far-field observer.
- A moving source can be detected within the band gap.
- Observed anomalous or inverted Doppler shifts for moving sources within band gaps.
Conclusions:
- The presence and motion of a source significantly alter sound detectability in periodic media band gaps.
- Anomalous Doppler effects challenge conventional understanding and offer new possibilities for acoustic manipulation.
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