Rare Book & Manuscript Library


Preserving the Audio Archive

The material on the LCAAJ audio tapes is unique. The field notes focus solely on selected linguistic features in the informant's responses and the tapes have not been transcribed, except for a selection included in the EYDES project. The wealth of information that the tapes contain thus resides solely on a fragile and aging medium.

The 5,755 hours of recording in the LCAAJ are stored on some 2,600 reels of tape produced in various countries between 1959 and 1972. The tapes were recorded at a variety of speeds under widely varying conditions. More than twenty different brands and sizes of tape stock have been used, including both acetate- and polyester-backed tape, and there are even thirteen hours of wire recordings. As is all too sadly known, acetate tape (used through the late 1960s) is a very impermanent medium for the recording of sound. Manufacturers' claims, and real-time experience indicate, that twenty years is the average functional life for such tapes. They begin to suffer edge curl, cracking and flaking, and binder decomposition, leading to loss of the recorded signal. The polyester tapes used since the late 1960s are also impermanent, suffering from sticky shed and other failures, and the tapes may stretch or break during playing or storage. Even before these problems set in, splice adhesives may leech to other portions of tapes of all types, and many tape types are subject to print through. Once deterioration begins, it cannot be stopped or reversed. The only solution is careful re-recording in such a way that as little as possible of the original sound is lost.

Since 1995 Columbia University Libraries has been gradually re-recording the tapes and creating digital copies. Support for this effort includes:

The preservation work consists of re-recording the original tapes onto new reel-to-reel tape, following nationally recognized preservation practices and guidelines, and the creation of digital use copies on CD. The preservation transfer is carried out at the Computer Music Center of the Columbia University Department of Music, a studio recognized nationally and internationally both for its advanced technical work and its care of archival sound collections.

The project adheres to the technical standards for audio preservation advocated by the Association for Recorded Sound Collections Associated Audio Archives Committee (ARSC-AAA), the Joint Technical Commission of the Audio Engineering Society (AES), the American National Standards Institute (ANSI), and the National Association of Broadcasters (NAB). As recommended by these organizations, the re-recording employs low noise, two-track polyester (1.5 mil) tape. The archival tape is recorded in real time at 15 inches per second (ips) to preserve maximum audio fidelity, with no splicing, with buffer-tape-pack at both ends, wound uniformly tails out (end out) onto slotless-hub 10 -inch metal reels. In order to keep the archival copies as true to the original recordings as possible, no manipulation of the original signal, such as noise reduction, filtering or other signal-processing techniques, is undertaken.

Each reel is "leadered" at the beginning with 30-60 seconds of blank tape. Following this leader is a 30-60 second test zone containing reference tones and azimuth tones, which in turn is followed by a second 30-60 seconds of "leader" tape (blank, no splicing). Paper or plastic leaders are not spliced on to the reels to fill the required lead time. No splices appear in the preservation master. The material being preserved follows the second leader in two-track double monophonic in one direction only.

The recording levels are monitored at all times by recording technicians to ensure the best possible signal-to-noise ratio on the final analog tape. All recording machines are calibrated and cleaned prior to each recording session. Equipment used for transfer meets standards established by the American National Standards Institute (ANSI), EIA (Electronic Industry Association) and the National Association of Broadcasters (NAB).

For more information on this project, contact the Columbia University Libraries Preservation Division.