Subjective Validity of Figures of Merit for Room Aspect Ratio Design

Attempts have long been made to classify a room's low frequency audio reproduction capability with regards to its aspect ratio. Common metrics used have relied on the homogeneous distribution of modal frequencies and from these a number of 'optimal' aspect ratios have emerged. However, most of these metrics ignore the source and receiver coupling to the mode shapes - only a few account for this in the derivation of a figure of merit. The subjective validity of these attempts is tested and discussed. Examples are given of supposedly good room ratios with bad performance and vice versa. Subjective assessment of various room scenarios is undertaken and a ranking order has been obtained to correlate with a proposed figure of merit