Yon Sylvain, Tanter Mickael, Fink Mathias
Laboratoire Ondes et Acoustique, Université Paris VII/ESPCI, CNRS UMR 7587, 10 rue Vauquelin, 75231 Paris Cedex 05, France.
J Acoust Soc Am. 2003 Mar;113(3):1533-43. doi: 10.1121/1.1543587.
New perspectives in audible range acoustics, such as virtual sound space creation and active noise control, rely on the ability of the rendering system to recreate precisely a desired sound field. This ability to control sound in a given volume of a room is directly linked to the capacity to focus acoustical energy both in space and time. However, sound focusing in rooms remains a complicated problem, essentially because of the multiple reflections on obstacles and walls occurring during propagation. In this paper, the technique of time-reversal focusing, well known in ultrasound, is experimentally applied to audible range acoustics. Compared to classical focusing techniques such as delay law focusing, time reversal appears to considerably improve quality of both temporal and spatial focusing. This so-called super-resolution phenomenon is due to the ability of time reversal to take into account all of the different sound paths between the emitting antenna and the focal point, thus creating an adaptive spatial and temporal matched filter for the considered propagation medium. Experiments emphasize the strong robustness of time-reversal focusing towards small modifications in the medium, such as people in motion or temperature variations. Sound focusing through walls using the time-reversal approach is also experimentally demonstrated.
可听声域声学的新视角，如虚拟声空间创建和有源噪声控制，依赖于渲染系统精确重现所需声场的能力。在房间给定空间内控制声音的这种能力直接与在空间和时间上聚焦声能的能力相关。然而，房间内的声音聚焦仍然是一个复杂的问题，主要是因为声音传播过程中在障碍物和墙壁上会发生多次反射。在本文中，超声领域熟知的时间反转聚焦技术被实验性地应用于可听声域声学。与诸如延迟定律聚焦等经典聚焦技术相比，时间反转似乎能显著提高时间和空间聚焦的质量。这种所谓的超分辨率现象是由于时间反转能够考虑发射天线与焦点之间所有不同的声路径，从而为所考虑的传播介质创建一个自适应的空间和时间匹配滤波器。实验强调了时间反转聚焦对于介质中小的变化（如人员移动或温度变化）具有很强的鲁棒性。通过时间反转方法实现穿墙声音聚焦也得到了实验证明。
