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An experimental evaluation of regular polyhedron loudspeakers as omnidirectional sources of sound

Multiple-driver dodecahedron loudspeakers are commonly used in room acoustics measurements as omnidirectional sources of sound. Yet they and other regular polyhedron loudspeakers become “multidirectional” above their omnidirectional cutoff frequencies (often near 1kHz). Because these cutoff frequencies normally fall within common measurement bandwidths, one might question whether anything is really extraordinary about the dodecahedron loudspeaker or whether another regular polyhedron geometry would actually produce better average omnidirectionality over these bandwidths. This paper explores these questions through measured data, analysis, and comparison of frequency-dependent directivities of several regular polyhedron loudspeaker prototypes. It provides insights into their radiation properties and introduces an alternative method of quantifying omnidirectionality: the area-weighted spatial standard deviation of radiated levels over a free-field measurement sphere. It compares this method to the ISO 3382:...