Signal Dependencies of the Immersion Sweet Area in Multichannel Loudspeaker Reproduction

Multichannel loudspeaker systems are generally optimized for a particular listening position—the so-called sweet spot. A sweet area around this position may be defined within which the reproduced sound field is judged to be similar—physically or perceptually—to what is observed in the sweet spot itself. Here, the sweet area is defined in terms of physical sound field features associated with the psychological construct of immersive musical experience, namely, diffuseness and interaural cross-correlation. Binaural and spherical impulse responses are measured in a grid around the sweet spot in a listening room, and deviations of the sound field features across the listening area are evaluated for multiple loudspeaker setups and playback signals. The dependency of sound field feature deviations on the interchannel correlation structure of the signals is analyzed. Deviations of diffuseness and the interaural correlation coefficient are found to be related to interchannel correlation. Subsets of loudspeakers in the reproduction setups whose correlations particularly impact the spatial variation of the sound field features are identified.