Development of an acoustic filter for parametric loudspeaker using phononic crystals

Peifeng Ji; Wenlin Hu; Jun Yang

doi:10.1016/j.ultras.2016.01.013

Development of an acoustic filter for parametric loudspeaker using phononic crystals

Ultrasonics. 2016 Apr:67:160-167. doi: 10.1016/j.ultras.2016.01.013. Epub 2016 Jan 28.

Authors

Peifeng Ji¹, Wenlin Hu¹, Jun Yang²

Affiliations

¹ Key Laboratory of Noise and Vibration Research, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
² Key Laboratory of Noise and Vibration Research, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China. Electronic address: jyang@mail.ioa.ac.cn.

PMID: 26855254
DOI: 10.1016/j.ultras.2016.01.013

Abstract

The spurious signal generated as a result of nonlinearity at the receiving system affects the measurement of the difference-frequency sound in the parametric loudspeaker, especially in the nearfield or near the beam axis. In this paper, an acoustic filter is designed using phononic crystals and its theoretical simulations are carried out by quasi-one- and two-dimensional models with Comsol Multiphysics. According to the simulated transmission loss (TL), an acoustic filter is prototyped consisting of 5×7 aluminum alloy cylinders and its performance is verified experimentally. There is good agreement with the simulation result for TL. After applying our proposed filter in the axial measurement of the parametric loudspeaker, a clear frequency dependence from parametric array effect is detected, which exhibits a good match with the well-known theory described by the Gaussian-beam expansion technique. During the directivity measurement for the parametric loudspeaker, the proposed filter has also proved to be effective and is only needed for small angles.

Keywords: Gaussian-beam expansion technique; Parametric loudspeaker; Phononic crystals; Spurious sound.