title: Noise reduction in tunnels by hard rough surfaces.
abstract: This paper examines the feasibility of using two-dimensional hard rough surfaces to reduce noise levels in traffic tunnels with perfectly reflecting boundaries. First, the Twersky boss model is used to estimate the acoustic impedance of a hard rough surface. Second, an image source model is then used to compute the propagation of sound in a long rectangular enclosure with finite impedance. The total sound fields are calculated by summing the contributions from all image sources coherently. Two model tunnels are built to validate the proposed model experimentally. Finally, a case study for a realistic geometrical configuration is presented to explore the use of hard rough surfaces for reducing traffic noise in a tunnel which is constructed with hard boundaries.
authors.affiliation: Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
authors.forename: Ming Kan
authors.initials: MK
authors.lastname: Law
authors.forename: Kai Ming
authors.initials: KM
authors.lastname: Li
authors.forename: Chun Wah
authors.initials: CW
authors.lastname: Leung
mesh_terms: D003198:Computer Simulation; D003252:Construction Materials; D005160:Facility Design and Construction; D005240:Feasibility Studies; D006244:Hardness; D008962:Models, Theoretical; D009038:Motion; D009624:Noise, Transportation / Q000517:prevention & control*; D011312:Pressure; D015203:Reproducibility of Results; D013016:Sound; D013018:Sound Spectrography; D013499:Surface Properties