I have now had a chance to compare the audio from the 2014 Criterion Blu-Ray, the 2014 Eureka! Blu-Ray, the 2007 Criterion DVD, and another track which I found online. It has PAL speedup, so I presume it is the audio from the 2008 R2/R4 Paramount DVD, which is what I will be referring to it as from now on.
2014 Criterion Blu-Ray
Criterion Wrote:The original monaural soundtrack was remastered at 24-bit from a 35 mm optical soundtrack print. Clicks, thumps, hiss, and hum were manually removed using Pro Tools HD. Crackle was attenuated using AudioCube's integrated workstation.
This track is very bad. Heavy noise reduction and so everything sounds extremely dead and muffled.
Spectrum:
https://i.imgur.com/gdSVXtf.png
Spectogram:
https://i.imgur.com/ZFTFjfM.png
2014 Eureka! Blu-Ray
Eureka's booklet makes no reference to the audio.
This track is certainly better than the one found on Criterion's blu, but is still very muffled and dull.
Spectrum:
https://i.imgur.com/kYpyChc.png
Spectogram:
https://i.imgur.com/hnvctEu.png
2007 Criterion DVD
Criterion Wrote:The soundtrack was mastered at 24-bit from the optical soundtrack negatives, and audio restoration tools were used to reduce clicks, pops, hiss, and crackle.
Once again, this track is an improvement. Not amazing, but acceptable. Less muffled than the blu-rays.
Spectrum:
https://i.imgur.com/ypP73OV.png
Spectogram:
https://i.imgur.com/suUfbe6.png
2008 Paramount DVD
Note that the source I found for this had re-encoded the audio at 128kbps
Even better still. It sounds more lively than the criterion DVD and much more so than the blu-rays. It sounds good, but I still think that it could sound better.
Spectrum (speed adjusted):
https://i.imgur.com/3iYdRP5.png
Spectogram (speed adjusted):
https://i.imgur.com/ocVog3k.png
I am planning on getting started syncing the paramount DVD's audio to the criterion blu at some point.