Technically, Layered Sound refers to the resultant soundwave from two disparate types of loudspeakers, wherein the first creates a longitudinal soundwave, and the second creates a transverse soundwave - both loudspeakers operating over .... specific frequency range.

Shelley Katz

Natural sound manifests two types of sound-waves: binaurally correlated and binaurally de-correlated waves. Binaurally correlated soundwaves are highly coherent, and among other things, permit us to determine where a sound source is located. Binaurally de-correlated soundwaves are highly incoherent, and among other things, permit us to estimate our distance from the source, or the nature and size of an acoustic space. .