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. 2016 Aug 26;6:32300. doi: 10.1038/srep32300

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Copyright © 2016, The Author(s)

This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

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(a) Prototype of flat reflective meta-surface (Sample 1) with phase array feeds consisting of 13 point-like sources. (b) Measured microphone sound pressure levels (SPLs) at the normal direction of a plane, which are located 1 m from speakers with a flat reflective surface, a hard-wall reflective surface, and no structure. (c) Measured polar SPL for flat surfaces with 1490 Hz speakers. (d) Prototype of convex reflective meta-surface Sample 1 with 140° exterior angle and phase array feeds consisting of 13 point-like sources. (e) Measured microphone SPLs at the normal direction of a plane, which are located 1 m from sources with a convex reflective meta-surface, convex hard-wall reflective surface, and no structure. (f) Measured polar SPL for convex surfaces with 1490 Hz speakers. Inset: The x′ axis indicates the direction with tilt angle α relative to the x-axis.