Blocking oblique wave sound transmission through a multi-element barrier using alternate resonance tuning

• Published in: The Journal of the Acoustical Society of America 2017-05, Vol.141 (5), p.3745-3745
• Main Authors: Fleming, Meredith C., Bliss, Donald B., Villa, Mauricio
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4988247

Alternate Resonance Tuning (ART) utilizes a structural barrier subdivided into dynamic panel subsystems with different resonant behaviors. The underlying idea involves adjacent panel subsystems tuned differently to take advantage of the outofphase vibratory behavior, causing the 180° phase shift at different frequencies. In the intermediate range between the two resonance frequencies, the panels vibrate out of phase, leading to strong cancellation of the transmitted sound field. The method has been demonstrated analytically and experimentally for waves striking a barrier at normal incidence. The current work considers the effectiveness of ART to block the transmission of incident oblique waves, and considers both discrete frequencies and angles, and more realistic broadband random incidence fields. The research goal is to show that flexibility and controlled resonant behavior in subsystems can substantially block sound transmission, even for low structural damping. The subsystems alter the vibrating surface wavenumber spectra to reduce coupling between the structure and the acoustic field. Not only is the transmission of incident oblique waves reduced, but the transmitted and reflected waves radiate at a variety of angles due to the modification of the surface wavenumber spectrum. Applications include the development of lightweight flexible sound blocking barriers for vehicles and architectural spaces.