Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
J Acoust Soc Am. 2012 Jul;132(1):261-70. doi: 10.1121/1.4726012.
Spherical microphone arrays have been recently used for room acoustics analysis, to detect the direction-of-arrival of early room reflections, and compute directional room impulse responses and other spatial room acoustics parameters. Previous works presented methods for room acoustics analysis using spherical arrays that are based on beamforming, e.g., delay-and-sum, regular beamforming, and Dolph-Chebyshev beamforming. Although beamforming methods provide useful directional selectivity, optimal array processing methods can provide enhanced performance. However, these algorithms require an array cross-spectrum matrix with a full rank, while array data based on room impulse responses may not satisfy this condition due to the single frame data. This paper presents a smoothing technique for the cross-spectrum matrix in the frequency domain, designed for spherical microphone arrays, that can solve the problem of low rank when using room impulse response data, therefore facilitating the use of optimal array processing methods. Frequency smoothing is shown to be performed effectively using spherical arrays, due to the decoupling of frequency and angular components in the spherical harmonics domain. Experimental study with data measured in a real auditorium illustrates the performance of optimal array processing methods such as MUSIC and MVDR compared to beamforming.
球形麦克风阵列最近已被用于房间声学分析，以检测早期房间反射的到达方向，并计算定向房间脉冲响应和其他空间房间声学参数。以前的工作提出了使用基于波束形成的球形阵列进行房间声学分析的方法，例如延迟和求和、正则波束形成和 Dolph-Chebyshev 波束形成。虽然波束形成方法提供了有用的方向选择性，但最佳阵列处理方法可以提供增强的性能。然而，这些算法需要具有满秩的阵列互谱矩阵，而基于房间脉冲响应的数据可能由于单帧数据而不满足此条件。本文提出了一种针对球形麦克风阵列的频域互谱矩阵平滑技术，该技术可解决使用房间脉冲响应数据时低秩的问题，从而便于使用最佳阵列处理方法。由于在球谐域中频率和角度分量的解耦，频率平滑被证明可以有效地在球形阵列中执行。使用在真实礼堂中测量的数据进行的实验研究说明了 MUSIC 和 MVDR 等最佳阵列处理方法与波束形成相比的性能。
