Speaker
Description
The concept of a diffuse sound field is long established and oft assumed in room acoustics. Metrics to quantify the ‘diffuseness’ of a given sound field also exist, and include cross-correlations between spaced sensors, the ratio of intensity to potential energy, and isotropy. Nonetheless, recent research has shown that there remains knowledge gaps, notably around the relationships between these metrics, their confidence intervals, the source layouts they inform, and even on some details of the underlying mathematical theory. In room acoustics, interest is often in quantifying the acoustic qualities of a space, for example in a reverberation chamber for absorption measurement. In the space launch environmental test sector, where spacecraft and payloads need to be qualified against high intensity sound fields representative of the launch environment, similar usage occurs. But here another more active use is also emerging, as the means to specify the sound field synthesis target in Direct Field Acoustic Noise (DFAN) testing systems, in which large arrays of high-powered loudspeakers positioned close to the test article produce the require noise spectrum. This paper will summarize approaches from that sector and some new developments in metrics and modelling.