title: Sound barriers from materials of inhomogeneous impedance.
abstract: Sound barriers are extensively used in environmental noise protection. However, when barriers are placed in parallel on opposite sides of a sound source, their performance deteriorates markedly. This paper describes a barrier made from materials of inhomogeneous impedance which lacks this drawback. The nonuniform impedance affects the way sound undergoes multiple reflections, and in the process traps acoustic energy. A proposed realization of the barrier comprises a closely spaced array of progressively tuned hollow narrow tubes which create a phase gradient. The acoustics of the barrier is theoretically examined and its superiority over conventional barriers is calculated using finite element modeling. Structural parameters of the barrier can be changed to achieve the required sound insertion loss, and the barrier has the potential to be widely used in environmental noise control.
authors.affiliation: Institute of Acoustics, Tongji University, No. 1239 Siping Road, Shanghai 200092, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute of Acoustics, Tongji University, No. 1239 Siping Road, Shanghai 200092, China.
authors.forename: Dongxing
authors.initials: D
authors.lastname: Mao
authors.affiliation: Institute of Acoustics, Tongji University, No. 1239 Siping Road, Shanghai 200092, China.
authors.forename: Wuzhou
authors.initials: W
authors.lastname: Yu
authors.affiliation: Institute of Acoustics, Tongji University, No. 1239 Siping Road, Shanghai 200092, China.
authors.forename: Zaixiu
authors.initials: Z
authors.lastname: Jiang