Exhibitions of Sound: The digital preservation of music
“We started changing the tapes eight or ten years ago. The first transfers we made were all to DAT. We found that DAT started deteriorating so we moved them to CDs. We didn’t think that was sufficient, so we moved to hard drives. That way it preserves it, hopefully forever.” —Sun Records CEO Shelby Singleton
Technologies change. Today’s solution could be tomorrow’s problem. Compared to printed words, audio recordings are still in their infancy. We’re still figuring it out. As mediums change, so too do the techniques used to preserve them.
Preservation can also encompass many different types of activities. Sometimes it can mean preserving old audio on new formats—moving vinyl albums to digital, for example—so that modern listeners can enjoy and learn from them. Or it could mean coming up with a new technique to extract audio from an old recording without damaging the master copy. Other times preservationists might be working on a way to enhance existing audio, restoring a lost classic in the process.
For the third story in our series on preservation, Playlist will explore some of the techniques and technologies researchers and archivists are using to preserve and restore older recordings so that we can appreciate them in the modern era.
The earliest recordings
Prior to the advent of magnetic recording, which allows for a record of audio to be preserved on tape, everything was recorded mechanically. In 1877, Thomas Edison invented the phonograph, which for the first time allowed people to capture sounds and play them back. The phonograph relied on phonographic cylinders rather than discs. Sounds were printed to a cylinder and played back when a stylus read the vertical impressions.
The earliest cylinders imprinted sound recordings on tinfoil, which was inherently unstable. Just a decade after its invention, the recording era saw its first major shift in technology with the advent of wax cylinder recording. The wax cylinder spawned a new industry, and cylinders began to be produced in large numbers. Although the cylinders were easy to imprint, they could only be made in small quantities and proved very hard to preserve.
Glenn Sage works to preserve these early recordings, he’s transferred about 4,000 cylinders to digital recordings to date. At his website, tinfoil,com, he’s published a variety of these historically significant early recordings, including turn of the century music recorded by Edison bands, 1908 campaign speeches by President William Taft and William Jennings Bryan, and the oldest playable recording in existence. (The site also has an excellent comprehensive history of wax cylinder recordings for those who want to learn more.)
“Quite a few years after [the invention of the phonograph], in 1888 Edison came up with the idea of a standardized wax cylinder that when recorded on will take the imprint in a warmer environment, and could be played back in regular room temperature at any time. They’re used up until about 1902,” Sage tells Playlist . “I work on those mostly because they tend to be one of a kind,. Even though there is some mass production they are pretty crude. They involve using one phonograph per take. You get ‘X’ number of recordings per take, and most of those were worn down or destroyed. The ones that survive today tend to be one of a kind.”
“I take a digital representation of what’s on the wax cylinder,” he says. “For sake of the preservation I don’t try to make it sound like I think it should sound; I just take what’s on the cylinder. If other people want to do noise reduction that’s cool, but I just take what’s on the cylinder.”
Unfortunately, the same problem that was true in the 1880s remains true today: the very act of playing back a cylinder hastens its destruction. Thus you can’t just play the cylinder on a vintage phonograph and record the audio to another medium. Using a system he designed to minimize contact, Sage captures the audio from wax cylinders to his PC running custom audio software.
“It’s light contact approach, meaning there is contact with my apparatus on the cylinders. Being that they’re wax cylinders they want to have as little contact as possible. Light contact has a lot of advantages in that I can do a lot of restoration quickly. Optically the results require digital filtering. From a preservationist’s standpoint, I find that less than ideal, since somebody has to decide how it should sound. But I have no doubt that an optical approach will be able to be feasible that will find a good balance. Another drawback with optical is that you can’t do the transfer in real time. As somebody who likes to preserve these things, one of the things that makes it fun is I can hear the recording.”
The optical scanning Sage refers to represents a huge leap forward in preserving some of these early recordings. At Lawrence Berkeley Laboratories, scientists have found a no-contact approach that optically scans in the impressions made on cylinder recordings and early records. The approach began when physicist Carl Haber had the idea to apply some of the same methodology used to scan in subatomic particles to audio preservation.
“I work with another guy named Vitaliy Fadeyev and at the time when we started this work, our main field of work was particle physics, and that’s still my main activity. We were using a whole bunch of various optical measuring metrology to build the instruments we used in our physics research, so we were very familiar with these surface optical metrology techniques. That’s just the tool kit we had in our work,” Haber tells Playlist . “We heard about the Library of Congress and the state of recordings, and that people didn’t necessarily want to touch them anymore.”
“It was on of these ‘Gee, why don’t they want to do it this way,’ moments. We said why don’t they use some of these optical measuring techniques that are used for other purposes and apply them to this. We did a bunch of tests, and wrote a paper about it. The Library of Congress was very responsive and engaged.”
Haber and Fadeyev use a precision optical metrology system normally used to study theoretic subatomic particles to create digital images of the etchings in old recordings, be they on wax cylinders or old 78 r.p.m. discs. Using both 2D and 3D scanning methods, they track the undulations in the grooves in records. Unlike methods that bounce a laser beam off of a record, optical scanning isn’t susceptible to the effects of dirt, damage, or wear.
In fact, not only does the process allow them to extract audio recordings from delicate and damaged media, but it also helps them to restore it to a more pristine condition. The digital images they produce can be enhanced to remove scratches and reduce other noise. For a good example of how the process can recover and restore an old recording, listen to the before and after versions of the 1912 recording of “Just Before the Battle, Mother.” Both of which sound far superior to the same recording played with a stylus.
“We try to turn the mechanical objects into digital images and use the computer to analyze those images and calculate what the needle would do. The method is completely non-contact so if you don’t want to physically touch it because it’s damaged or delicate—that’s one advantage. And another, if the medium is broken you can’t read it with a needle, but you can take the pieces of it and put them back together on the computer. You can deal with certain media that otherwise; it’s hopeless.”
“When you speak to people in the archives there are two words people use. One is preservation and what that means is taking something and stabilizing it. Obviously that’s a priority for some of the more valuable recordings. The other is access. Our method addresses preservation by giving a very high resolution method to capture a highly defined image that can be analyzed to extract the sound,” says Haber. “Access is taking a large collection of 100,000 discs and digitizing them so people can get access to them. That’s the kind of process that requires a lot of mass digital conversion work. Our process doesn’t require a needle. It’s more like Xerox mentality.”
The Library of Congress is providing the bulk of the funding for the research, Haber says, along with the Mellon Foundation, and the National Endowment for the Humanities. Currently, they’re working to create a scanner for the Library of Congress that will allow its trained technicians to scan in a large number of recordings. Haber says the National Archive and Records Administration is interested in applying the work to plastic dictation belts on which many historically significant government recordings are stored.
Beyond the grooves: modern restoration
As technology advanced beyond the mechanical era, cylinders and discs were abandoned in favor of recording to magnetic tape. Although it was a tremendous leap forward, some of the same problems true of cylinders are also true of tape. Tape breaks down over time. As copies are made, quality is degraded. And as we learned in our last article, there’s even the issue of mush.
Yet preservationists are also working on ways to preserve recordings from the modern era. Often, this means trying to correct errors that were either introduced over time, or by the original recording process itself. Like Haber and Fadeyev, Jamie Howarth, of Plangent Processes is doing exciting new work restoring classic audio from the modern era,
“People thought tape was good, but of course it scratches. Film as it deteriorates, especially the magnetic stock from the 50s will break down and turn to vinegar and misshapen plastic. There’s all manner of gross errors in these old films and tapes that we try to correct.”
Howarth developed a digital restoration process that fixes speed and pitch issues and removes FM distortion from older recordings on both film and tape. By finding and removing the mechanical noises made during the original recording process, Howarth is able to produce a copy that more closely resembles a modern master recording. He has worked on restoration projects for everything from landmark musicals from the golden age of cinema to Billy Joel.
“Essentially, what our process depends on is finding something in the recording outside of the audio range that we can capture and track and use as a super-clock,” Howarth tells Playlist . “Film is really mechanical. It’s stiff and mechanically noisy in and of itself, then you roll it over sprockets and teeth and all this other stuff and it winds up in the audio. They took an approach where we would re-render the audio based on the clocking we could pull off the tape. We then adapted that so we can find rotor noises and motor noises, bearing noises, noises that the whole mechanical system made. We find those and track them and remove them and pitch variations in these old recordings.”
“We also found out that very, very small amounts of higher frequency flutters are very common in tape and film recordings. The spec for wow in flutter was developed in the 50s and they just sort of believed in that below a certain frequency there was no audibility. For years many of us who made analog tape, we knew that we were making copies that looked flat, but didn’t sound flat. We have discovered that it is a psycho-acoustic phenomenon based on the flutter where the bearings and motor add dirt and grunge. That’s why the generation loss things have tapes that measure flat but don’t sound flat. We’re able to track those very small sounds and flutters, which moves it one generation closer to the master.”
Ultimately, no matter what the technique, preserving audio is not just a goal in and of itself. It isn’t—or should not be—preserved merely so that it can be archived and studied. Rather, the purpose of it is to provide all of us, researchers, music fans, and history buffs, with an interactive window on the past that helps us better understand where we came from. They connect us with our past, and enliven our future.
“A lot of these [recordings] haven’t been played for three generations,” says Sage. “So nobody alive knows what they sound like. When you listen to something old and it comes across as new and different, it’s exciting.”
For more on the preservation of our musical heritage see Part 1: Exhibitions of sound: Finding America’s musical treasures and Part 2: Exhibitions of sound: The economics of salvation.
Mathew Honan is a San Francisco-based writer and photographer. His work has also appeared in Macworld, Wired, Time, and Salon.