Deep background

TV viewers with impaired hearing get especially irritated when background
sounds drown out dialogue—especially crowd noise during sports
commentaries. Now that we have digital television broadcasting, says the Hearing
Enhancement Company of Virginia, adjusting the relative level of dialogue to
background noise should be easier (WO 01/65888). HEC points out that in a system
in which the signal is always digitally compressed for transmission, and
reconstituted in the receiver, background and dialogue sounds can be processed
separately. Your receiver could then have a knob to vary the ratio of voice to
background sound.