The advent of broadband and tunable acoustic metamaterials, amenable to be fabricated into flat panel geometry, offers broad, emerging possibilities for room acoustics. In particular, the fine tuning of surface acoustic impedance becomes possible to optimize specific room acoustic goals. In this initial simulation study we examine the possibility of minimizing the averaged level of energy density ($L_e$), both globally and locally in an enclosed room. The relationship curve between surface impedance and global $L_e$ shows an optimal value that can reduce $L_e$ by about $15$–$20\mathrm{dB}$ over a wide audible frequency regime. Moreover, partial coverage of the room surface by the optimally tuned acoustic metamaterial already demonstrates considerable effectiveness. We compare and verify our numerical model with the statistical-diffusive acoustics model and find good agreement in the high-frequency regime. In the low-frequency regime, the energy inhomogeneity caused by wave interference can be utilized to create a quiet zone for specific targeted frequency by optimally tuning the surface impedance values at discretized locations on the four walls.

中文翻译：

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可调谐超材料表面将室内声能降至最低

宽带和可调谐声学超材料的出现，可被制成平板几何形状，为室内声学提供了广泛而新兴的可能性。特别是，表面声阻抗的微调变得可能，以优化特定的房间声学目标。在此初始模拟研究中，我们研究了最小化平均能量密度水平的可能性（${\mathrm{大号}}_{Ë}$），无论是在全球还是本地，都在封闭的房间中。表面阻抗与整体阻抗之间的关系曲线${\mathrm{大号}}_{Ë}$ 显示出可以降低的最佳值 ${\mathrm{大号}}_{Ë}$ 大约 $15$–$20\mathrm{D\; b}$在很宽的可听频率范围内。而且，通过最佳调谐的声学超材料对房间表面的部分覆盖已经显示出相当大的有效性。我们将统计模型与统计扩散声学模型进行比较和验证，并在高频范围内找到了很好的一致性。在低频状态下，通过优化调整四壁离散位置上的表面阻抗值，可以将由波干扰引起的能量不均匀性用于创建特定目标频率的安静区域。