Experimental characterization of a shape optimized acoustic lens: Application to compact speakerphone design

Peter Risby Andersen; Gyeong-Tae Lee; Daniel Gert Nielsen; Junghwan Kook; Vicente Cutanda Henríquez; Niels Aage; Yong-Hwa Park

doi:10.1121/10.0017859

Experimental characterization of a shape optimized acoustic lens: Application to compact speakerphone design

J Acoust Soc Am. 2023 Apr 1;153(4):2351. doi: 10.1121/10.0017859.

Authors

Peter Risby Andersen¹, Gyeong-Tae Lee², Daniel Gert Nielsen¹, Junghwan Kook¹, Vicente Cutanda Henríquez³, Niels Aage⁴, Yong-Hwa Park²

Affiliations

¹ GN Audio A/S & Jabra, Audio Research, Lautrupbjerg 7, 2750 Ballerup, Denmark.
² Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea.
³ Centre for Acoustic-Mechanical Micro Systems, Department of Electrical and Photonics Engineering, Technical University of Denmark, Ørsteds Plads, Building 352, DK-2800, Kgs. Lyngby, Denmark.
⁴ Centre for Acoustic-Mechanical Micro Systems, Department of Civil and Mechanical Engineering, Technical University of Denmark, Koppels Allé, Building 404, DK-2800, Kgs. Lyngby, Denmark.

PMID: 37092940
DOI: 10.1121/10.0017859

Abstract

This work presents the shape optimization and subsequent experimental validation of an acoustic lens with application to a compact loudspeaker, such as found in commercial speakerphones. The shape optimization framework is based on a combined lumped parameter and boundary element method model using free form deformation geometry parameterization. To test the optimized design, the loudspeaker lens is three-dimensionally printed and experimentally characterized under anechoic conditions on a finite baffle with respect to its off-axis frequency response. The overall tendencies of the frequency responses agree well between measurement and simulations within the optimization frequency range and at low frequencies. The optimization process is applied to a model including acoustic lumped parameter approximations. The shortcomings of the assumptions made in the model are revealed by laser Doppler vibrometer measurements of the loudspeaker driver and modelling of the mechanical vibrations of the lens.