This descriptor that is designated DL 2 and measured in dB states the gradient of the sound propagation curve. Another descriptor designated DL f and also measured in dB, states how the sound level at a certain distance behaves in relation to the sound level at the same distance in a free sound field, i.e. without reflecting objects. By increasing the DL 2 value and simultaneously reducing the DL f value, the distance to the place where the sound level is no longer disturbing (distracting) will have decreased.

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ThisdescriptorthatisdesignatedDL2andmeasuredindBstatesthegradientofthesoundpropagationcurve.AnotherdescriptordesignatedDLfandalsomeasuredindB,stateshowthesoundlevelatacertaindistancebehavesinrelationtothesoundlevelatthesamedistanceinafreesoundfield,i.e.withoutreflectingobjects.ByincreasingtheDL2valueandsimultaneouslyreducingtheDLfvalue,thedistancetotheplacewherethesoundlevelisnolongerdisturbing(distracting)willhavedecreased.