Theoretical and experimental analysis of the diffuseness in room sound fields

房间脉冲响应具有极其复杂的精细结构，涉及到时间和空间特征。因此，在应用声学中，经常使用漫射场的概念。漫射场的理论概念在室内声学和混响室声学测量中起着非常重要的作用。本项目的目标是定义和实验验证一个度量，用于在非相干声波和衰减曲线的各向同性意义上表征房间声场中接收器位置的扩散。该项目的部分内容是与三个合作伙伴（罗斯托克大学、巴黎IRCAM和哥本哈根DTU）合作安排的。该建议通过评估房间声场中依赖于时间和频谱滤波方法的平面波分布，通过比较有效的阵列信号处理方法，通过探索已知空间信号处理方法的潜力，并扩展到施罗德衰减曲线的空间分解，从而扩展知识。最后，混响室鉴定和校准的扩散度量将在轻微变化的声源和麦克风定位（误差灵敏度分析）中使用统计模型进行测试，重点是吸收系数的测量。为了确定实际方面，如所需的空间分辨率和（十二面体）扬声器指向性在这种测量中的影响，将使用MIMO（阵列对阵列）房间脉冲响应测量的高阶实验系统。这些结果与阵列信号处理以及一般的室内声学，特别是标准吸收测量有关。

Room impulse responses have an extremely complicated fine structure as concerns temporal and spatial features. In applied acoustics, therefore, often the idea of a diffuse field is used. The theoretical concept of the diffuse field plays a very important role in room acoustics and in acoustic measurements in reverberation chambers. The objective in this project is the definition and experimental validation of a metric for characterization of the diffuseness at receiver positions in a room sound field in the sense of isotropy of incoherent sound waves and of decay curves. Parts of this project are arranged in collaboration with three partners (Rostock University, IRCAM Paris, and DTU Copenhagen). This proposal leads to the extension of knowledge by evaluating the Plane Wave Distributions in room sound fields depending on temporal and spectral filter approaches, by comparing efficient array signal processing methods, by exploration of the potential of the known spatial signal processing methods and extension towards spatial decomposition of Schroeder decay curves. Finally, the diffuseness metric for reverberation room qualification and calibration will be tested with statistical models in slightly varied source and microphone positioning (error sensitivity analysis) with the focus on measurement of absorption coefficients. In order to identify practical aspects such as the influence of the required spatial resolution and the (dodecahedron) loudspeaker directivity in such measurements, a high-order experimental system for MIMO (array-to-array) room impulse response measurement will be used. The results are relevant for array signal processing as well as for room acoustics in general, and for standard absorption measurements in particular.