Volume VII Number 1, August 2000

National Library Service For The Blind and Physically Handicapped: Digital Plans and Progress

John Cookson
Lloyd Rasmussen
National Library Service for the Blind and Physically Handicapped (NLS)
The Library of Congress


NLS produces about 2,000 talking books and 50 magazines per year on specially formatted cassette tape for free distribution to a readership of about 764,000. Cassettes and special players are delivered by U.S. Postal Service from a network of 138 participating libraries. To control the cost of technical obsolescence and to meet patron and sponsor expectations, NLS will replace this analog system with a digital system over the next ten years.


The increasing prevalence, popularity, and economy of digital electronics motivates NLS to work rapidly toward a completely digital audio service. This means using digital methods throughout the production and distribution stream, from studio recording of digital original masters and digital collection management to digital product distribution and playback. The length and complexity of the transition are consequences of size. NLS annually circulates about 22,000,000 audio books and magazines nationwide and supports the use of about 721,000 cassette playback units. Further information on NLS, including the agencyís mission, organization and history can be found on the NLS website; see, particularly, the area titled About NLS, where "Basic Facts About NLS" and other summary information can be found.


In response to the high-risk digital-transition challenge, NLS has published a summary master plan and has made significant progress toward its implementation. The plan can be found on the NLS web site under Digital Talking Books: Planning for the Future. Of particular interest are the articles Planning for the Future and Twenty Steps to Next-Generation NLS Technology. In our synopsis of implementation presented below, we will refer to specific topics mentioned in the cited articles.


NLSís implementation activity has been focused on three major project areas: our Digital Audio Development Project, our standards-setting effort, and local research and development.


Immediately following its inception in September 1998, this NLS committee identified three areas for pursuit of our digital future: cost modeling, product simulation, and collection access.

Cost modeling

One of the essential components of technology-transition decision-making is relative cost. In the simplest terms, we must know the cost of providing service using the incumbent technology, we must be able to project this cost out to a ten-year horizon, and we must be able to estimate the cost of the digital alternative. To this end, we have engaged a commercial firm with expertise in cost modeling to build a software tool that will enable us to make the required estimates and support decision-making.

When a technical advancement, such as dense solid-state memory is introduced into the consumer entertainment market, a plethora of competitive products are introduced at premium prices. Market pressures and the quest for standards cause losers to disappear, while demand causes winners to fall in price, sometimes precipitously. On the other hand, older technology can experience price escalation and availability problems as demand declines. Our model is designed to capture and depict these phenomena so that we can identify more economical technology as well as the best time and level of investment to recommend. When subject to critical scrutiny, the modelís inputs and computational procedures must be able to engender credibility and confidence. As of this writing, working in consonance with the contractor, NLS has drafted a data dictionary that defines the name, meaning, and source of each data element used in the model.

We have also reviewed some of the computational procedures that the model will use to compare various technologies that NLS might consider. We anticipate the review process to be completed by mid-March and delivery of a prototype by mid-May. The prototype will allow users to evaluate the input-output interface, check computational validity, and find bugs. Although it is very unlikely that NLS will implement a CD-ROM-based system, for purposes of test and verification, the design team is under contract to demonstrate a comparison between the use of cassette tape and CD-ROM. The model should be fully operational by mid-September, and we look forward to making it an evolving working tool that will be updated and maintained throughout the technology-transition process.

Collection Access

The very last step in the technology-transition process is to gradually replace cassette players with portable digital playback devices. This final step in the transition will be built upon changes in digital production, storage, and distribution methods, that are made far in advance of providing digital players. Our plans are to have a digitally mastered collection of about 10,000 titles available no later than 2008. To this end, NLS has published its intent to require all of its contract producers to phase in digital original mastering over the next four years. In support of this requirement that will involve the writing and review of technical specifications, NLS studio personnel are testing a digital mastering system in house. This effort is intended to build expertise while providing the first titles for a digital collection, and will be followed by another in-house studio installation and the exploration of efficient methods for quality-checking of digital material.

In parallel with the innovation in digital mastering, NLS is exploring the selective conversion of audio in the analog collection to a digital format. In one multistate center we have installed a system that efficiently uses analog-to-digital conversion to make digital cassette copies of open-reel analog masters. Besides building expertise in efficient and high-quality digital conversion, the computer-based system permits archiving on CD-ROM and quality enhancement of older recordings. Testing and evaluation of these capabilities is presently in progress.

As digital original masters become available from the NLS recording studio and contract producers, we intend to experimentally store them on media and in formats designed to facilitate a particular function. There will be a shelf or archive copy on CD-ROM in the same format as the digital original master, most likely a wav file of 16-bit PCM sampled at 44.1 kHz. There will also be a version stored on a large magnetic disk array (not connected to the Internet) that could be an exact copy of the archive copy or a version that has been formatted by a data-reduction algorithm such as MPEG Layer 3. The archive will teach us about problems in long-term storage, and the disk array will permit experiments in formatting and data reduction. A prototype system with about 90 GB of storage is presently in place at NLS. This system cannot be connected to the Internet because the technology for the protection of intellectual property is in development. This kind of technology comes under the general heading of Digital Rights Management (DRM), and is the subject of intense discussion in the publishing and library communities. There are many complex issues on the table, and we are following events closely so that any system that we eventually adopt will be acceptable to rights owners.

Product Simulation

The production, management, and playback of digital products involves the development and maintenance of computer software. As this assertion suggests, required software can be divided into the three identified categories. Our approach to audio production software is to use off-the-shelf products that drive digital mastering equipment and produce wav files. Using other production software to help build a digital talking book (DTB) from the audio files, plus whatever part of the corresponding text is available for integration, is an area that will receive more attention as the need for product simulation comes into focus. Programs that can help generate and validate XML, as well as programs to time-align audio with the corresponding text, will be evaluated.

For the management of digital products our initial approach will be to use conventional file management software found in popular computer operating systems. As the collection expands we will consider the use of software more attuned to our particular data set. In this case there may be an opportunity to use some of the software presently used to manage the audio material that is part of the Library of Congressís Digital Repository Project.

One of our most challenging and interesting software requirements is the need to simulate future playback equipment. This software will allow us to check the feasibility of putting various features into portable hardware, assist us in the development of user interfaces, and permit us to test the compatibility of DTBs. We have done some experiments locally with software components such as systems for interactive control of playback speed without pitch distortion, but have yet to build a fully functional system. We intend to survey the commercial software market to determine approximate cost and level of interest. Our request for information will appear in the Commerce Business Daily during the second quarter of this calendar year. We expect to be able to identify the required software expertise at an affordable price. An appreciation for the complexity of this undertaking is apparent from the DTB feature list.


Under the auspices of the National Information Standards Organization, an affiliate of the International Standards Organization, NLS is leading a group of experts in the development of a DTB standard. For a more detailed discussion of why and how the standards process was begun, please see Talking Books: Toward a Digital Model, our paper delivered at CSUN 3/97.

Because the development of this standard plays such a central role in our digital strategy and because it has such pervasive and persistent implications, we treat it with a separate article in this special ITD issue. Please see Digital Talking Book Standards Developed by NLS and Partners under NISO Auspices.


In support of our progress toward a fully digital future, NLS has undertaken an 8-point in-house technical research and development program. The thrust of this program is threefold: evaluate potential DTB components, build expertise competent to develop technical specifications, and maintain a clear view of where consumer products are headed. Specific areas under study include audio data reduction algorithms (e.g. MPEG Layer 3), variable rate playback methods, text-to-speech programs, and user interfacing hardware. For a complete list of topics please see our planning document, Digital Talking Book: Technical Activity Planning.

Besides building and maintaining digital expertise, our R&D program has yielded some interesting results. In the area of variable rate playback, for example, we have tested an algorithm from Enounce Inc. called TimePlay and found it to produce high-quality audio with real-time user control. We have conducted experiments in the use of MPEG Layer 3 and found that at a 10-to-1 data reduction ratio few listeners can distinguish the original from the processed audio. We have recently acquired and listened to Lernout & Hauspieís state-of-the-art speech synthesis software called RealSpeak, noting performance that is good and interesting, but not equivalent to rendition by a talented narrator. For more detail on progress in these and the other R&D areas please see Digital Talking Book Technical Activity: Summary Report.

Some of the areas that we are closely following in the consumer market place include the emergence of electronic books, both audio and text-based. Of particular interest are new reading models offered by Audible and Gemstar. Audible plans to target the auto commuter market with frequently updated material from newspapers and magazines as well as novels and other leisure reading. They distribute encrypted spoken audio via the Internet to proprietary devices for playback on an auto sound system. Their significant investors include Microsoft, and there will be an effort to offer audio synchronized with text on Microsoft-supported platforms. Gemstar, the company with a dominant interest in TV Guide and VCR Plus, has recently acquired Softbook and RocketBook. Both of these enterprises market text-based reader devices that display Internet-delivered encrypted content that is accessible only on a specific reader. Gemstar plans to expand reader options, include audio capability, and mount a large advertising campaign. They hope to get about 35 million consumer units into service within about 5 years. One possible sales strategy will be modeled on the cell phone, where the hardware is offered at well below manufacturing cost with the purchase of a minimum value of content. At NLS we have purchased both Softbook and RocketBook readers as well as an Audible player and sample material for evaluation. At this time the players are not suitable for use by blind and physically handicapped individuals, but if the market is opened to competing devices, there is reason to evaluate any promising product. Our R&D program will include these evaluations. A de facto industry standard for content may also be a competitive outcome that we will both monitor and influence through participation in Open eBook discussions. Open eBook is a consortium of companies that have drafted a standard for electronic text so that it can be displayed by any device conforming to the standard. For more details please see the Open eBook website.


Converting NLS from an analog cassette-based talking-book system to a digital enterprise with a readership of over 764,000 is a complex and challenging task. We are approaching it in a step-by-step manner as outlined in the plan cited above and view it as an opportunity to enhance user satisfaction through the introduction of advanced technology.

Cookson, J. & Rasmussen, L. (2000). National Library Service for the blind and physically handicapped: Digital plans and progress. Information Technology and Disabilities E-Journal, 7(1).