The Study Of The Extraordinary Acoustic Transmission Phenomenon Through The Perforated Plate

In recent years, for the wavelength of light transmission phenomenon in the field of research is more and more arouse people’s interest, the researchers kept all kinds of physical model tries to explain the light from the physical nature of abnormal phenomenon of transmission.At the same time this kind of abnormal phenomenon of transmission of light also save a lot of related physical phenomena and potential applications, involving areas such as surface enhanced Raman spectra, negative refraction phenomenon, invisibility cloak, magneto optical effect, high density optical data storage light gathering effect, and so on.Sound and light and electromagnetic wave have the nature of the fluctuations, so people also has been trying to find a classical wave transmission phenomenon.Until recent years, sound wave abnormal transmission phenomenon was officially confirmed in the experiment.Later, the researchers through comparing with the exception of light transmission phenomenon, puts forward several widely recognised physical model to explain the abnormal sound transmission phenomenon.One of the most important is, based on the theory of Fabry-Perot resonance coupling interference.But as a result of sound and light in the abnormal phenomenon of transmission of huge different, for the fundamental physical mechanism still needs extensive research and discussion.Sound waves through stimulate subwavelength aperture diffraction wave, high order dissipation mode, the multiple scattering wave cavity for abnormal sound transmission phenomena such as contribution and role you need to do more research. At the same time for the process of the phenomenon of abnormal sound transmission Angle dependence, narrow transmission bands features such as also need to find out root cause from the physical mechanism.This paper is aimed at traditional subwavelength perforations, abnormal phenomenon of sound transmission, set up a corresponding physical model, through the coupling interference theory and methods of impedance matching, electrical, acoustic analogy, the transmission coefficient is derived theoretically and structure size, the relationship between acoustic parameters and so on.Try to find out inherent physical mechanism of the phenomenon of abnormal sound transmission.In addition to the traditional subwavelength perforations, abnormal sound transmission phenomenon existing in the strong Angle dependence problem, according to the characteristics of helmholtz resonator, this paper proposes a have abnormal sound transmission phenomenon at the same time and does not depend on the new features from the Angle of subwavelength structure of perforated plate. And through the corresponding theoretical derivation, numerical calculation and experimental verification, proved that the structure of the unique features. Through detailed theoretical analysis of perforated plate structure, we find out the following facts:1, under the condition of subwavelength slit of perforated plate is high order dissipation mode.It is because of high order dissipation mode introduced a DengXiaoSheng impedance, led to abnormal sound transmission.If long-term incident acoustic wave is greater than the structure size, higher order dissipation mode are difficult to inspire, the perforated plate was mainly affected by one-half wavelength resonance transmission phenomenon, would not show the abnormal phenomenon of transmission.2, high dissipation modal and transmitted wave coupling interference of sound wave incident Angle sensitive role.As the incident Angle is different, its coupling also will show the differences.Because of this, the traditional perforations, abnormal sound transmission phenomenon to show strong Angle dependent characteristics.3, in view of the traditional strong perforations in the abnormal phenomena of sound transmission Angle dependent on characteristics of reason, we designed two cavity in the structure.By introducing the acoustic impedance of resonant cavity, make the structure satisfy impedance matching relations, realize the abnormal sound transmission phenomenon.Due to introduction of acoustic impedance at the same time make the transmission bands corresponding to a longer wavelength, high dissipation mode are difficult to inspire, to eliminate the influence of Angle to the transmission frequency band, implementation does not depend on the Angle of the abnormal phenomenon of sound transmission.4, moreover through analyzing the traditional theory of perforated plate, each size we also basic figure out its structure on the relationship between the abnormal transmission frequency band.