change intensity

alter, change, modify - cause to change; make different; cause a transformation; "The advent of the automobile may have altered the growth pattern of the city"; "The discussion has changed my thinking about the issue"

dim, dip - switch (a car's headlights) from a higher to a lower beam

pipe down, quiesce, quiet, quiet down, quieten, hush - become quiet or quieter; "The audience fell silent when the speaker entered"

louden - become louder; "The room loudened considerably"

soften - make (images or sounds) soft or softer

sharpen - make (images or sounds) sharp or sharper