Smithsonian will restore hundreds of the oldest sound recordings

The IRENE people are trying machine learning to recognize and remove dust and scratches. That sort of thing is for reading archival items once and generating a archival digital copy at some very high sampling rate and resolution. That's then down-converted for listening.

Many early cylinder records sound quite good when played back with modern equipment. It turns out that most of the distortion came from the mechanical playback process, where huge stylus pressures were used to get enough motion to directly drive a speaker membrane. The recording process was making reasonably good recordings.

(History of electronics: "We need more volts." "We need more gain." "We need more frequency." "We need more stability." "We need more power capacity." "We need more gates". "We need less heat.")

CDs, DVDs, etc. have error-correcting codes, so they don't have this problem.

[1] https://en.wikipedia.org/wiki/Laser_turntable

In my mind this seems like the difference between the visual representation of the waveform an audio editor shows vs the literal bits encoding the actual audio.

In practice one can approximate the original sound from the image of the waveform, but in most cases it will likely lack in resolution relative to a medium engineered for playback.

> The [1980s production] prototype revealed an interesting flaw of laser turntables: they are so accurate that they "play" every particle of dirt and dust on the record, instead of pushing them aside as a conventional stylus would.

In the same Wikipedia entry:

> A similar technology is to scan or photograph the grooves of the record, and then reconstruct the sound from the modulation of the groove revealed by the image. Research groups that developed this technology include:

IRENE is the one used by the Smithsonian. https://irene.lbl.gov/links/audio-files-for-june-24-2021-pre... has some of the recordings recovered by IRENE.

I've wondered if regular cameras would get good enough that you could take a picture of a record with your phone and have it play the sound. IRENE and VisualAudio links show that a microscope is needed, so no, it doesn't seem "phone"-o-graphic playback will be any time soon.