Wave Motion 70 (2017) 101–112 Contents lists available at ScienceDirect Wave Motion journal homepage: www.elsevier.com/locate/wavemoti Sound transmission through a periodically voided soft elastic medium submerged in water Gyani Shankar Sharma a,∗ , Alex Skvortsov b , Ian MacGillivray b , Nicole Kessissoglou a a School of Mechanical and Manufacturing Engineering, UNSW Australia, Sydney, 2052, Australia b Maritime Division, Defence Science and Technology Group, Melbourne, 3207, Australia highlights • Analytical and numerical models to study sound transmission through a periodically voided soft elastic medium are developed, in which the analytical model is based on effective medium approximation theory. • Attenuation of sound transmission through the periodically voided elastic medium is shown to be related to the monopole resonances of the voids. • The effect of strong and weak coupling of cylindrical void resonances on transmission characteristics is presented. article info Article history: Received 17 May 2016 Received in revised form 21 October 2016 Accepted 31 October 2016 Available online 3 November 2016 Keywords: Periodic voids Elastic medium Monopole resonance Sound transmission abstract Analytical and numerical models are developed to study sound transmission through a periodically voided soft elastic medium submerged in water. The analytical model is based on homogenisation theory which allows modelling of the voided material as a homogeneous material using effective material parameters. The numerical model is based on the finite element method. A single layer of voids as well as multiple layers of voids along the direction of propagation of sound are considered. Attenuation of sound pressure is attributed to the monopole type resonance of the voids. The effect of strong and weak coupling of void resonances on the transmission characteristics is presented. Strong coupling of resonance of voids is shown to result in broadband attenuation of sound. The advantages and limitations associated with each predictive technique are briefly discussed. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Acoustic wave scattering from a void in a rubber-like medium (e.g. a medium with shear modulus much smaller than compressible modulus) can exhibit monopole resonance similar to that produced by scattering from a bubble in a fluid [1,2]. Periodically voided elastic media can exaggerate this phenomenon and have traditionally been employed to develop subwavelength acoustic absorbers [3,4]. One of the important practical applications of these materials is as an acoustic coating for maritime vehicles to reduce transmission of machinery noise and acoustic reflection [5–8]. Recently, periodically voided materials (phononic crystals) have been widely studied as a conceptual model for metamaterials with unusual acoustic properties such as negative stiffness, frequency gaps, anomalous reflection, etc. [3–5]. For a given rubber-like ∗ Corresponding author. E-mail address: gyanishankar.sharma@unsw.edu.au (G.S. Sharma). http://dx.doi.org/10.1016/j.wavemoti.2016.10.006 0165-2125/© 2016 Elsevier B.V. All rights reserved.