Serving Digital Audio for Oral History Collections

1. Serving Digital Audio for Oral History Collections Eric Weig Head, Digital Programs University of KentuckyCoalition for Networked Information (CNI) Task Force Meeting, December 4-5, 2006.

2. Overview • Background • Basics of Digitizing Audio & Standards for Preservation • Analog to Digital Audio Workstation • Delivery to Users • Staffing and Costs • Future Directions

3. Background

4. Background The University of Kentucky houses the Louie B. Nunn Center for Oral History, established in 1973. Over the last three decades, more than 6,500 interviews have been conducted on topics including the Frontier Nursing Service of Eastern Kentucky, Family Farming, Civil Rights, and Kentucky Politicians. Over the years, part-time employees and student workers have diligently transcribed, in first draft form, nearly half of the entire collection.

5. 2-Year Pilot Project: September 2005-September 2007 • Funding from Oral History Program Endowment. • 40 hours a week of student wages • $10,000 for equipment • Sept. 2005-June 2006 • The Digital Programs Department began work on establishing methodologies and standards for digitizing oral history audio tapes and archiving digital master files. • July 2006-June 2007 • Build online interface and data conversion tools to deliver audio and transcript segments via the World Wide Web.

6. Goals for Greater Access • Create and archive high quality digital masters from analog originals. • Create lower quality, compressed deliverables from digital masters for online access. • Allow full-text searching of final and first draft transcripts. • Allow access to finalized transcripts in their entirety when available. • When transcript text is available for searching, localize hits to within 5 minute audio segments. • Use automation wherever possible to maximize limited resources and establish an economical, scalable digital conversion methodology.

7. Basics of Digitizing Audio & Standards for Preservation

8. Factors Effecting Quality • Digital audio quality is expressed as: • the sampling rate or the number of times per second the amplitude of a sound wave is measured (kHz), and • the range of numbers used to record each measurement (bit depth). • Highest frequency pitch that a digital audio sample can record is ½ of the sampling rate. • i.e. 44.1 kHz audio CDs can record frequencies only up to 22.05 kHz.

9. Factors Effecting Quality, cont. • Recording at a sampling rate higher than 44.1 kHz (44,100 samples per second), is not effective in preserving more information for analog audio cassette tapes, as they are not capable of recording frequencies above 22.05 kHz. • Most experts agree that most humans cannot hear pitches above 20 kHz and resolve only between 15 and 17 bits per sample. • Possible bit depths for digital audio are 16 or 24. • 24 bit files double the storage space required to adequately preserve the digital files.

10. MASTER FILE File Format: Pulse-code Modulation.wav Channels: (2) Stereo Bit rate: 16 Frequency: 44.1kHz Conversion from Analog to Digital

11. 2 Master Files are Created The first WAV file archived comes directly off the hardware with no additional software manipulation performed. A second, edited WAV file is archived with minor enhancements performed to reduce hiss and boost voice. Both master WAV files are archived to a mass storage backup system as well as onto portable TB drives and DVDs.

12. Analog to Digital Workstation

13. Digital Conversion Workstation • The basic digital reformatting process typically involves four devices: • an analog audio playback device, • an analog-to-digital (AD) converter, • a computer to process the digital signal, and • a device for digital file storage. • Optionally, a mixing device, such as an audio mixing board, can be utilized between the analog audio playback device and the AD converter to enhance the audio signal before any digital processing takes place.

14. Digi-Design 002 recording/mixing board/AD Dell PC – Pentium 4, 2.24 GHz, 1GB RAM, 40GB internal HD (programs only), 200GB internal HD (audio files) Audigy sound card Alesis monitors and power amplifier Tascam 112MKII Cassette Deck Adobe Audition software Cost: ~ $4,000 Digital Conversion Workstation, cont.

15. Delivery to Users

16. Delivery to Users: Emphasis on Getting to the Audio • A level of emotion accessible in the audio is devoid in the printed transcript. • No transcript is perfect. • Final transcripts are expensive to produce. • Compress and lower quality to make derivative for fast Web delivery: • LAME MPEG (MP3) 2.5 Layer III • Channel: (1) Mono • Frequency: 11 kHz • Compression: 7 to 1 • Use first draft or final transcript to localize search hits, then offer access to easily digestible audio segment (5 minute chunk) containing the search hit.

17. Modes of Online Delivery • Digital Oral History Interviews can be ingested into the online delivery system with variable degrees of access dependent upon whether or not a transcript has been created. • digital audio file only • unedited “first draft” transcript and digital audio file • finalized transcript and digital audio file

18. Search Results

19. Digitization Process Overview 1 STEP 1 | STEP 2 | STEP 3 | STEP 4 | STEP 5 • Create, XML encode, and segment transcript into tape parts (finalized transcript files are also converted to PDF format). (manual + automated) • Digitize audio and create master and derivative files (manual + automated) • Gather metadata from Accession FileMaker database to create bibliographic records. (automated) • Set 5 minute time stamps within the transcribed text. (manual + automated) • Chunk derivative files into 5 minute segments. (automated)

20. Digitization Process Overview 2 input • Script is run to mostly automate the XML encoding on finalized transcripts. • Students input simple place holder text markers ‘{chunk}’ at five minute marks in the transcript. • An automated script then detects the place holders and converts them into time stamps based upon the total duration of the audio file and five minute marks. • Online Delivery System dynamically chunks the audio files on-the-fly into 5-minute segments based upon a time stamp for the entire audio file. output

21. Technology for Online Delivery • Redhat Linux server. • University of Michigan DLXS software. • SOX: Dynamically chunks audio files into 5 minute segments. • LAME library for decoding MP3 format. • Hosted by the Kentuckiana Digital Library, a state-wide digital library cooperative managed by the University of Kentucky Libraries.

22. Staffing and Costs

23. Staff • 2 student workers dedicate a total of 35 hours a week to complete analog2digital conversion, metadata gathering, transcript conversion and transcript chunk marking for time stamps. • 40 hrs a week are dedicated to ‘first draft’ transcription by volunteers and student workers. • Programmer worked 40 hours to complete custom production scripts and interface enhancements. • One librarian and an oral historian designed interface. • One librarian quality controls and indexes data after students have completed their work.

24. Digital Production Cost • September 2005-September 2006 • 700 audio tape sides at $14.50 per conversion. Production of master and derivative audio files only and time to complete backups. • October 2006-present • 100 audio tape sides at $16.00 per conversion. Production of master and derivative audio files, metadata and transcript preparation including marking for time stamps.

25. Future Directions

26. Future Directions • Allow users to employ a slide bar to dynamically slice the audio file into any desired duration of time segments. • Allow users to change the character length of the KWIC view around search hits. • Link interviews to available Encoded Archival Description collection descriptions. • Investigate audio to text conversion technology for creating “first draft” transcripts without manual transcription. • Migrate to new version of DLXS allowing for the use of METS to proliferate more interoperability.