ExtremeTech saw demonstrations of a couple of new sound technologies that aim to improve HDTV audio quality. The reporter said it was pretty impressive.
At the show, I saw impressive demos of a number of technologies, including SRS's TruVolume solution and TruSurround HD ; Dolby Volume, and Analog Devices' SoundMax. THX has a similar technology called THX Loudness Plus, while Audyssey offers a technology called Dynamic Volume for leveling sound, along with Dynamic EQ, designed to improve the sound.
Some of these solutions are just pure leveling solutions, meaning they understand the level you want the volume, and then adjust the volume from different sources to match it. Others model the sound, attempting to do things like making the dialog more understandable. There are big debates over which approaches are right; some say that the director and sound staff on a movie know best how they want it to sound, so all you should do is control the volume. Others think the sound range should be adjusted at different volume levels. As near as I can tell, SRS TruVolume is more focused on leveling; THX more on modeling, and the others on both.