Upmixers extract ambience already in recordings, not synthesized reverb
Evidence
It needs to be emphasized that, when playing stereo music through these algorithms, we are hearing “ambience extraction,” not reverberation synthesis. All of the reflected and reverberated sound that is reproduced in the surround channels was in the recording. It is just redirected to the side and/or rear loudspeakers rather than being reproduced exclusively through the front channels. Consequently, it generally sounds more natural, although it can also sound exaggerated with some recordings; stereo recordings were not designed for this form of reproduction. In order to get a sense of spaciousness in stereo reproduction through two loudspeakers, more “ambiance” (poorly correlated sound) is often recorded than would have been required if surround channels had been anticipated. The solution: use the remote control and turn the surrounds down. — , Toole, Floyd E - Sound reproduction-…, 1736
Categorization
- DEFINE: Clarifies the common misconception that upmixing adds synthetic reverb; it merely redirects ambience already present.
- SHARE: A portable correction for anyone in audio who mis-takes upmix = synthesis.
- XREF: connects to: Upmixer quality depends on matching parameters to the specific recording; Stereo-to-binaural upmixing splits direct and ambience signals for separate spatial processing
Related
- Upmixer quality depends on matching parameters to the specific recording (similarity 0.94)
- Stereo-to-binaural upmixing splits direct and ambience signals for separate spatial processing (similarity 0.88)
- Stereo upmixing quality varies because it depends on the pairing of recording and upmixer. (similarity 0.84)
- Upmixers that overuse the center channel degrade the stereo music soundstage. (similarity 0.84)
- Stereo signals can be processed for headphones to recreate natural binaural sound fields (similarity 0.79)
- Limited human spatial resolution allows plausible upmix from fewer source channels (similarity 0.79)
- Human spatial resolution limits make stereo-to-multichannel upmixing perceptually plausible. (similarity 0.79)