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Preservation of Analog Collections through Digitization

The Preservation of Analog Oral History Collections through Digitization

by Sarah Cunningham

 

The deterioration of analog sound carriers is a significant danger to Oral History Collections. This dilemma coupled with the obsolescence of vintage playback creates a need for the digitization of oral history recordings.

In addition to preserving recordings, most archives have a strategic mission to provide access to the resources in our collections. Now that many cultural history documents are freely disseminated in digital format researchers require easier access to more documents and records online.

 

New Form of Technical Expertise    

Over the past decade, audio engineers and technical specialists involved in the digital transfer of analog sound recordings created standards for sampling rates, bit depths, computer properties, playback, and the education of sound engineers. The AES (Audio Engineering Society) and the IASA (International Association of Sound and Audiovisual Archives) are valuable sources of preservation literature and guidelines for audio archives. Their papers draw from the depth of knowledge of their members and an established vetting process.

The American Library Association defines preservation in the digital era as a process that:

Combines policies, strategies and actions to ensure the accurate rendering of authenticated content over time, regardless of the challenges of media failure and technological change. …  preservation policies document an organization’s commitment to preserve digital content for future use; specify file formats to be preserved and the level of preservation to be provided; and ensure compliance with standards and best practices for responsible stewardship of digital information. (http://www.ala.org/alcts/resources/preserv/defdigpres0408)

This serves as a model for the preservation of oral histories in the digital age.

Establishing a Digitization Program to Preserve Oral Histories

The best starting point to launch a program to prioritize, digitize and preserve your recordings is to survey your collection. A survey that reveals the content and condition of oral histories in your collection often evolves into an assessment of the needs and a future “plan of action” for  the collection.  By understanding the extent of holdings and the chemical content and structure of the recordings, a plan for remedial actions and treatment can be established. Documentation of the collection can be used to write grants for the preservation of your holdings.

A survey of oral history collections should include:

  • Type of carrier— cylinder, tape (reel-to-reel or cassette), disc, etc. This will help identify the type of playback needed.
  • Physical structure of recording—magnetized metal particles; tapes with backing material of paper, acetate or mylar, molded wax; cores of discs of aluminum, glass, or cardboard .
  • Chemical composition—wax, plastic, shellac, acetate, metal particles, etc.
  • Manufacture of carrier—cores of discs (aluminum, glass) molded wax, etc.
  • Condition of the media—this is crucial to the process and gathers information used in the decision to transfer in-house or to send it to a specialist.

Creating a workflow

When transferring analog sound files for oral history collections, a workflow should be established to outline the standards, processes, equipment, and storage for media records.

The first step for a preservation project to digitize a collection is to decide to transfer the recordings in-house or to outsource to a vendor. Each collection is unique and your survey will give a foundation for the decision. If the collection will be out-sourced, the workflow should include:

  • Inspect the collection before sending,
  • Document the shipment and sign a loan form,
  • Quality control of the finished product – a preservation master
  • Ingest into a preservation storage system,
  • Back-up files for the preservation masters.
  • Create access copies CDs or mp3s for online access, and
  • Catalog/index recordings.

For in-house digitization, as well as outsourced projects, it is imperative to create master files using established standards (established by the AES and IASA). This includes:

  • Sampling (a digital snapshot) of analog recordings at 96,000 samples per second with a bit depth of 24.
  • Preserving metadata—managerial, technical, descriptive, structural, and administrative information embedded in the file and/or in a database that corresponds to the digital file.
  • Implement a program to run checksums and other authentication methods to check the integrity of the file over time.

Access copies for researchers are usually prepared at a lower resolution (CD quality 44,100 samples per second and a bit depth of 16) for easier distribution.

A recent OHDA survey highlighted a lack of technical expertise in oral history collections. With this in mind, collection managers have an obligation to translate the workflow created for their collections to all involved with the materials.

All personnel working with the recordings should understand the strategies, processes, and action to be taken to ensure the preservation of a recording. Most metadata must be gathered and noted at the time of the oral history interview and steps need to be taken at each point to guarantee the integrity of the recordings and information carried with it.

In addition to the digitization and preservation of the bit stream, it is important to preserve the original carrier of the recording. Information regarding the recording, the brand and vintage of the media and information about the recording are included on the carrier. In addition, as the field matures, new methods for extracting sound from the carrier will emerge. Methods for non-contact sound extraction from grooved media are now in use at the Library of Congress.

 Playback

Playback equipment for audio is becoming obsolete. Vintage formats are becoming a higher priority in digitization programs as they are becoming atypical and the machines used to play the recordings are difficult to obtain and expensive to repair and maintain. Fortunately, there are vendors specializing in specific formats who can complete the analog-to-digital conversion.

A brief history of recording formats (see Morton’s book at the end of this chapter) is necessary to aid in identifying the type of carrier and to locate proper playback for the media. Some modern machines can be modified to play older formats and older discs can be played by using appropriate styli to playback the vintage grooves.

The digitization of recordings

The digitization of audio has been an important part of audio archives since the late 1990’s.  The current standard for the preservation and digitization of recordings has been established at 96,000 samples per second with a bit depth of 24, usually expressed as 96 kHz/24 bits. Several software programs are designed to capture audio at preservation quality. The playback machine used must be of the highest quality to extract the optimum audio signal. With the master recordings preserved and stored as an uncompressed bitstream as outlined in the EBU document tech 3285, [1] access copies can be created for researchers.  While there are several different types of files associated with audio, the bwf [Broadcast wave format – a modification of the WAVE format with a “Broadcast Audio Extension” extension added] is generally used as the preservation file since it provides a space in the header of the file to embed metadata pertaining to the file.  (IASA TC-04 2nd ed.)

Maintenance and storage of digital files

Policies and procedures unique to the collection and/or the host institution should be established including:

  • The creation of an infrastructure to hold the digital audio files (this should be simple, with a flexible framework to store the records in an organized manner);
  • The operation of migrating, emulating, and refreshing files;
  • The education of staff; and
  • The back-up of files to appropriate locations.

All personnel need to understand the concept of how files are kept, distributed, and stored at their institution.

The Need for the Technical Education of Oral Historians

The educational needs for staff members can be met with a variety of conferences, workshops, and training. The Association for Recorded Sound Collections, the International Association for Sound Archives, the Audio Engineering Society along with the Association of Moving Images, the Music Librarian’s Association, and the Society of American Archivists now have training sessions, workshops, and publications designed to educate all levels of technical and non-technical staff.

The National Recording Preservation Board (NRPB) at the Library of Congress established best practices, educational programs, publications, and workshops for the training of sound archivists and others interested in the field.  http://www.loc.gov/rr/record/nrpb/. The NRPB’s and the Library of Congress’ research combining scientific principles with anecdotal information helps audio archivists realize the extent of efforts needed to preserve sound recordings. Oral histories are a vital part of our cultural history and need to be preserved. By building a preservation program through digitization, the recordings will be transferred before the carriers become obsolete. This offers oral historians and researchers further access to the recordings.

The information provided below represents the current publications, standards, and best practices for audio digitization and the preservation of recordings.

Audio Engineering Society. “The proceedings of the aes 20th international conference: Archiving, restoration and new methods of recording, Budapest, Hungary.” New York: AES. 2001. http://www.aes.org/publications/conferences/.

Association for Recorded Sound Collections (ARSC). Education and training in audiovisual archiving and preservation. 2004.  http://www.arsc-audio.org/etresources.html.

Audio Preservation Bibliography

http://www.loc.gov/rr/record/nrpb/nrpb-presbib.html.

Casey, M. FACET: Format characteristics and preservation problems. Bloomington, IN:  Indiana University, 2007. http://www.dlib.indiana.edu/projects/sounddirections/facet/facet_formats.pdf (PDF, 5.15 MB).

Casey, M., and Gordon, B. “Sound directions: Best practices for audio preservation.” In Sound directions: Digital preservation and access for global audio heritage. Bloomington, IN: Indiana University, 2007. http://www.dlib.indiana.edu/projects/sounddirections/papersPresent/index.shtml.

Federal Agencies Guidelines Initiative. Library of Congress, 2009. http://www.digitizationguidelines.gov/audio-visual/.

International Association of Sound and Audiovisual Archives. Guidelines on the production and preservation of digital audio objects: Standards, recommended practices, and strategies, 2nd ed. Auckland Park, South Africa: International Association of Sound and Audiovisual Archives, IASA-TC04, 2009. http://www.iasa-web.org/audio-preservation-tc04.

Morton, David. Sound recording: The life story of a technology. Westport, Connecticut: Greenwood Press, 2004

National Recording Preservation Board, Library of Congress. “Capturing analog sound for digital preservation: Report of a roundtable discussion of best practices for transferring analog discs and tapes.” Council on Library and Information Resources, March 2006.http://www.clir.org/pubs/reports/pub137/contents.html.

Pohlmann, Ken C. Measurement and evaluation of analog-to-digital converters used in the long-term preservation of audio recordings Paper written for the roundtable discussion convened by the Library of Congress and Council on Library and Information Resources on behalf of the National Recording Preservation Board, March 10-11, 2006, in Washington. D.C. (PDF, 257 KB).

TAPE: Training for Audiovisual Preservation in Europe. http://www.tape-online.net/ (2010).

Standards

AES22-1997 (r2008): AES recommended practice for audio preservation and restoration — Storage and handling — Storage of polyester-base magnetic tape. http://www.aes.org/publications/standards/.

AES28-1997 (r2008): AES standard for audio preservation and restoration — Method for estimating life expectancy of compact discs (CD-ROM), based on effects of temperature and relative humidity (includes Amendment 1-2001). http://www.aes.org/publications/standards/.

AES38-2000 (r2005): AES standard for audio preservation and restoration — Life expectancy of information stored in recordable compact disc systems — Method for estimating, based on effects of temperature and relative humidity. http://www.aes.org/publications/standards/.

AES41-2009 (r2005): AES standard for digital audio — Recoding data set for audio bit-rate reduction. http://www.aes.org/publications/standards/.

AES49-2005: AES standard for audio preservation and restoration — Magnetic tape — Care and handling practices for extended usage.http://www.aes.org/publications/standards/.

ANSI/PIMA IT9.26-1997 Imaging Materials – Life Expectancy of Magneto-Optic (MO) Disks – Method for Estimation, Based on Effects of Temperature and Relative Humidity. http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=44129.



[1] Most sound archives use the bwf. A modification of the WAVE format with a “Broadcast Audio Extension” chunk added. http://tech.ebu.ch/docs/tech/tech3285.pdf

Citation for Article

APA

Cunningham, S. (2012). The preservation of analog oral history collections through digitization. In D. Boyd, S. Cohen, B. Rakerd, & D. Rehberger (Eds.), Oral history in the digital age. Institute of Library and Museum Services. Retrieved from http://ohda.matrix.msu.edu/2012/06/preservation-of-analog-collections-through-digitization/.

Chicago

Cunningham, Sarah. “The Preservation of Analog Oral History Collections through Digitization,” in Oral History in the Digital Age, edited by Doug Boyd, Steve Cohen, Brad Rakerd, and Dean Rehberger. Washington, D.C.: Institute of Museum and Library Services, 2012, http://ohda.matrix.msu.edu/2012/06/preservation-of-analog-collections-through-digitization/

This is a production of the Oral History in the Digital Age Project (http://ohda.matrix.msu.edu) sponsored by the Institute of Museum and Library Services (IMLS).  Please consult http://ohda.matrix.msu.edu/about/rights/ for information on rights, licensing, and citation.

Permanent link to this article: http://ohda.matrix.msu.edu/2012/06/preservation-of-analog-collections-through-digitization/

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