The Night of the Hunter (1955)

Criterion booklet:
"The monaural soundtrack was taken from the 2001 UCLA Film & Television Archive restoration, supervised by Robert Gitt and by John Polito of Audio Mechanics. This restoration was painstakingly constructed from a 35mm composite master positive, a variable-density soundtrack negative of the film's music and effects track, a projection print, and many rolls of 35mm magnetic film containing fully edited dialogue recordings. All of this audio was digitized at 96 kHz 24-bit by Simon Daniel and Peter Oreckcinto at DJ Audio in Studio City, CA. Additional restoration was performed by Criterion using Pro Tools HD."

Robert Gitt's 2001 photochemical restoration was released on DVD that year by MGM. The Arrow and Wild Side blu-rays use a more recent scan of that restoration, but the audio was subjected to noise reduction.

This further filtered audio track is the basis of Criterion's track, but Criterion decided to do even more work on it. Some more noise reduction, some slight scene-specific low-frequency attenuation. Funnily enough, even the modern day MGM lion at the beginning has been muffled severely.

(I don't have the Arrow blu-ray, but there's little reason to suspect it's different than the Wild Side.)

So, the Criterion blu-ray audio is a needlessly filtered version of the Wild Side/Arrow, but the Wild Side/Arrow are themselves further processed versions of the base 2001 Robert Gitt preservation that MGM put out on DVD presumably without any additional changes.

What Dr. Svet Atanasov had to say about the Criterion blu-ray:

The new English LPCM 1.0 track conveys excellent depth and stability that will undoubtedly impress those of you who own the old R1 SDVD release of Night of the Hunter and can compare it with Criterion's Blu-ray release. There is certain crispness and color to the audio that is indeed very pleasing. The dialog is also clean and stable. Lastly, I did not detect any pops, cracks, hissings, or audio dropouts to report in this review.

The amount of detail on the MGM DVD audio track missing from the Wild Side/Arrow (and, of course, the Criterion) blu-rays is very noticeable. The opening credits music knocks the wind out of you and dialogue is clear and less muffled than on the blu-rays.

However, there is quite a bit of crackle underlying all dialogue throughout the MGM track--enough to annoy most people, surely. I don't mind it that much. If removing it necessitates making the soundtrack murky and uninvolving (characteristics falsely associated with age), I'd rather put up with some crackle.

Leo Enticknap in Film Restoration: The Culture and Science of Audiovisual Heritage:

...This is a major ethical issue for restorers. Market research has shown consistently that many consumers who are not experts on audio technology regard the presence of noise as a major defect, and are far more tolerant of a poor quality signal than they are of the presence of noise. The Vitaphone expert Robert Gitt commented, "I've heard some commercial releases on CD of old jazz recordings which have been excessively filtered. The noise is all gone, but the musicians sound very mechanical and dry and robotic. They sound like mechanical men playing." It is possible to avoid the 'mechanial and dry and robotic' impression by using less noise reduction, an option more technologically literate listeners tend to prefer, and furthermore a closer listening experience to the one that audiences to an initial release of a Vitaphone film in the late 1920s using the system's original playback equipment and auditoria would have had. But within the overall customer base for a DVD (for example) these technologically literate consumers tend to be in the minority, and therefore restorers frequently find themselves under commercial pressure to apply more noise reduction that they would like.