Measurement of room spatial correlation functions using spherical microphone arrays

• Published in: The Journal of the Acoustical Society of America 2018-09, Vol.144 (3), p.1883-1884
• Main Authors: Elko, Gary W., Meyer, Jens
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.5068258

The study of acoustic spatial correlation functions has been ongoing since early analytical development and experiments were done by Farran and Hills in 1952. The measurement of sound diffuseness using spatial correlation functions has been discussed previously by the authors in 2009. It has been conjectured that audio rendering of the spatial impression of a soundfield is related to the degree of correlation between the microphones used to record the soundfield. The correlation between the recorded channels is related to the diffuseness of the sound field. Many different models of diffuse fields have been described and are based on a definition that involves incoherent sound coming uniformly from all directions. Schroeder surmised that as the modal density exceeds three overlapping modes in one modal bandwidth that the random uniform model can be utilized in practice. In order to obtain measured room spatial correlation functions one has to ensemble average either multiple source or receiver positions. With eigenbeamforming spherical microphone arrays these functions can be ensemble averaged by utilizing multiple steered beampatterns with at least two spaced arrays. We will show some theoretical spatial correlation functions for different beampatterns and orientations and compare these to measurements made in a real room.