Resonant Sound Transmission Research Articles

Sound Insulation of Single-Layer Glazing, Single- and Double-Glazed Windows

The analysis of known analytical solutions to the problem of calculating transmission the sound insulation of one- two- and three-layer glazing in comparison with the results of laboratory measurements is presented. The wave theory of sound transmission through single-layer and multi-layer enclosing structures with air gaps is used. Based on calculations of sound insulation of single-layer glazing, it is shown that the theory underlying the methodology of GOST R EN 12354-1–2012 “Acoustics of buildings. Methods for calculating the acoustic characteristics of buildings based on the characteristics of their elements. Part 1. Sound insulation of air noise between rooms”, most adequately takes into account the processes of non-resonant and resonant sound transmission. Its use in the formulation of models of sound transmission through double and triple glazing, taking into account internal losses and the influence of resonant processes, made it possible to obtain analytical solutions to the problem of sound insulation of single-chamber and double-chamber double-glazed windows, which showed good convergence with the experimental results. The proposed method for calculating sound insulation through single- and double-chamber double-glazed windows can be used in engineering calculations after additional studies of internal losses in multilayer glazing, as well as additional measurements of a number of “standard” types of glazing to verify the methodology.

Experimental and Numerical Investigations of the Vibration and Acoustic Properties of Corrugated Sandwich Composite Panels

To explore the lightweight structures with excellent vibration and acoustic properties, corrugated composite panels with different fiber reinforcements, i.e., carbon and glass fibers, were designed and fabricated using a modified vacuum-assisted resin infusion (VARI) process. The vibration and sound transmission loss (STL) of the corrugated composite panels were investigated via mode and sound insulation tests, respectively. Meanwhile, finite element models were proposed for the verification and in-depth parametric studies. For the vibration properties of the corrugated composite panels, the results indicated that the resin layer on the panel surface, despite the extremely low thickness, showed a significant effect on the low-order bend modes of the entire structure. In addition, the difference in the mode frequency between the panels consisting of different fiber types became more and more apparent with the increase of the frequency levels. For the sound insulation property of the panel, the initial frequency of the panel’s resonant sound transmission can be conveniently increased by increasing the layer thickness of surface resin, and the fraction of fiber reinforcements is the most predominant factor for the sound insulation property, which was significantly improved by increasing the thickness of the fiber cloth. This work can provide fundamental support for the comprehensive design of vibration and acoustics of the composite sandwiched panel.

Coupled-mode theory for stationary and nonstationary resonant sound propagation

In this paper, we present a complete analytical derivation of the equations used for stationary and nonstationary wave systems regarding resonant sound transmission and reflection described by the phenomenological coupled-mode theory. We calculate the propagating and coupling parameters used in coupled-mode theory directly by utilizing the generalized eigenwave-eigenvalue problem from the Hamiltonian of the sound wave equations for the problem of a one-dimensional isolated on-channel resonance. This Hamiltonian formalization could be beneficial and could potentially model and parameterize a broad range of acoustic wave phenomena. We demonstrate how to use this theory as a basis for perturbation analysis of complex resonant scattering scenarios. In particular, we form the effective Hamiltonian and coupled-mode parameters for the study of sound resonators with background moving media. Finally, we provide a comparison between coupled-mode theory and full-wave numerical examples, which validate the Hamiltonian approach as a relevant model to compute the scattering characteristics of waves by complex resonant systems.

The prediction of flanking sound transmission below the critical frequency

Although reliable methods exist to predict the apparent sound reduction index of heavy, homogeneous isotopic building constructions, these methods are not appropriate for use with lightweight building constructions which typically have critical frequencies in or above the frequency range of interest. Three main methods have been proposed for extending the prediction of flanking sound transmission to frequencies below the critical frequency. The first method is the direct prediction which draws on a database of measurements of the flanking transmission of individual flanking paths. The second method would be a modification of the method in existing standards. This method requires the calculation of the resonant sound transmission factors. However, most of the approaches proposed to calculate the resonant sound transmission factor work only for the case of single leaf homogeneous isotropic building elements and therefore are not readily applicable to complex building elements. The third method is the measurement or prediction of the resonant radiation efficiency and the airborne diffuse field excited radiation efficiency which includes both the resonant and the non-resonant radiation efficiencies. The third method can currently deal with complex building elements if the radiation efficiencies can be measured or predicted. This paper examines these prediction methods.

Theory of resonant sound transmission through small apertures on periodically perforated slabs

An analytical theory for sound transmitting through apertures that are slits or holes periodically pored on one- or two-dimensional rigid panels is developed in small-aperture approximation, with all coefficients of reflection and transmission given explicitly in concise and easily calculable forms. We utilize acoustical impedance to quantitatively describe the effect of sound diffraction by both surfaces of a perforated slab on the aperture resonance. We show that diffraction induced reactance Xa, which is acoustically inertant (Xa>0) for incident wavelength λ longer than the period Λ of the perforated slab, can become infinitely large as λ approaches to Λ. We further show that the singularity of Xa not only causes the already known full reflection of acoustic waves at λ=Λ, but also drastically changes the aperture resonance leading to the extraordinary acoustical transmission that was observed in recent experiments. With this understanding, tuning the resonant transmission becomes practically feasible in applications of the resonant transmission phenomenon.

Sound transmission across duct constrictions with and without tapered sections

The sound power transmission loss across duct constrictions with linearly tapered sections is studied with the finite element method. Results show that the acoustic energy distributions of transmitted waves at high frequency depend critically on the exit configuration of the constriction. The corresponding strengths of these waves are very much affected by the entrance setup of the constriction. The difference between inlet and outlet impedance of a constriction leads to weaker resonant sound transmission.

Significance of resonant sound transmission in finite single partitions

The resonant sound transmission has been regarded to be negligible in finite single partitions compared to the non-resonant transmission. In this study, the sound transmission coefficient is reconsidered by using the general modal expansion method in order to estimate the contribution of resonant components to the whole sound transmission at frequency bands below the coincidence frequency. By investigating the band-average difference between the total and non-resonant transmission losses, the validity of the aforementioned assumption is discussed. In the analysis, the participation factor comprised of size, thickness, and loss factor is employed. Based on this factor, the valid range of neglecting the resonant sound transmission is proposed, in which the inclusion of the resonant component makes difference being less than 1 dB.