Many people know about how each rerelease of Star Wars starting in the late ’90s added more scenes and tweaked the look of the films, but I’ve only recently discovered how different the audio is in later versions. Save Star Wars has a good overview of the different audio mixes the films have contained over the years:
In 1985, Ben Burtt supervised a stereo remix for home video, taking into account the acoustics of television audio (as this was the pre-home theatre days it has the least dynamic range of any mix). In 1993, the sound was remixed in stereo again, this time “sweetening” the audio with added effects in Star Wars.
So four years before the special editions would add Jabba to A New Hope and make Greedo shoot first, George Lucas was already having changes made to the movies. (And of course, it began long before that, with the addition of “Episode IV: A New Hope” to the opening crawl when the film was rereleased in theaters a year before The Empire Strikes Back came out.) There’s some information on what sounds were added/changed in the 1993 mix on originaltrilogy.com and also a neat page with samples to listen to comparing the differences between the stereo and mono mixes.
In 1997, the films were remixed in 5.1 surround and released on Laserdisc in Dolby Digital (and VHS in stereo). In 2004, the sound was remixed in Dolby Digital yet again for DVD release.
However–the history-making original audio has never been officially released by Lucasfilm, excepting the two-decades-out-of-print stereo mix. These are the audio mixes that the Academy of Motion Picture Arts and Sciences would have heard when they awarded the films for sound design and mixing, and they are also the audio mixes that everyone was blown away by during the original theatrical experience.
The films were eventually release in surround sound, but adding new scenes to the films necessarily meant that the soundtrack would have to be altered accordingly. The changes weren’t limited to just adding new bits of music, though. The whole audio mix was remastered. “hairy-hen” on originaltrilogy.com, on the 2004 DVD audio mix:
I tend to find it pretty difficult to describe in concrete terms exactly what’s wrong with the 2004 mix, because it’s so impossibly screwed up and unrecognisable that I don’t even know where to begin. It’s like the sound effects are all muddled and mushed together somehow, and there’s no breathing room to distinguish them from anything else. To me it sounds as though they utterly killed the high frequencies, probably as a way of overcompensating for tape hiss, and boosted the low end to an absurd level. If you play the original mix through an EQ with the bass all the way up and the treble all the way down, it starts to resemble the remix. (Note that I’m not talking about the really low bass found in an LFE channel, I mean the higher bass registers in the main channels.)
TServo is quite correct in calling it ‘unfocused’, because there’s really no balance between the different elements. Listen to the hallway shootout in particular, and try to find the 'rhythm’ of the laser battle. Guess what: it isn’t there. In the original, the different types of laser sounds coming from the rebels and the stormtroopers have a sort of back and forth going on, reflecting the camera angle and the position of the characters onscreen. In a way you can hear the 'story’ of what’s happening from which sound effects are dominant at each particular moment. In the remix, the rhythm is gone and the 'story’ of it is indistinguishable. Background tracks for characters firing their blasters from farther away are mixed at exactly the same level as those in the foreground (ie, far too loud), meaning that everything becomes jumbled and indistinguishable.
So, the newer mixes aren’t any good, but they’re the only ones in surround sound. Enter hairy-hen, who has spent a good deal of time trying to reproduce the original audio mixes by reverse engineering early home releases that were mixed down to stereo from the theatrical surround sound versions. It’s fascinating to read about. Much more in his post on originaltrilogy.com.