noun

(often in legal use) the ending, reduction, or lessening of something.

noise abatement

subsiding,dying away,dying down,dying out,dropping away,dropping off,lessening,easing,easing off,decrease,diminishing,moderation,decline,declining,fade,dwindling,cooling off,tailing off,petering out,tapering off,wane,waning,ebb,relenting,desisting,weakening