Temporal progression of the source density of the acoustic transient released by the flare SOL20110730T02:04-M9.3 in the 9.0–11.0 mHz spectrum, showing that emission from the northwestern kernel, ﹩{A}_{\mathrm{NW}}﹩, of the composite western acoustic source significantly precedes (see panel (a)) that from the south-eastern kernel, A_SE (see panel (c)). Acoustic emission from the single-kernel far-eastern source, B, appears to peak about halfway between the peaks of the individual kernels of the composite western source.