College Park, MD . . . The Advisory Committee on Preservation of the National Archives and Records Administration (NARA) met on Thursday, September 21, to evaluate recent technological advances in the recapturing of sound from audio recordings. The permanent members, who heard presentations from representatives of both the public and private sectors, specifically addressed the issue of whether current advancements in the field could recapture sound from the famous "18½-minute gap" in the Nixon White House tape recordings.
After several hours of discussion describing the initial tests performed on the "18½-minute gap" tape in 1974, the current state of audio technology, and avenues for further investigation, the committee reached the following conclusions and recommendations:
- We know of no available non-destructive technique that will extract the signal that was erased.
- Based on our discussions and our reading of the 1974 report to Judge Sirica, we support the conclusions of the 1974 report that it is highly unlikely that one can recover the erased speech from the tape.
- There have been suggestions of techniques that might be applicable to the recovery of speech from erased analog magnetic tape; an approach should be taken by NARA to create a simulation tape to be made available for proof of concept. (Proof of concept would be a demonstration that it is possible to recover a defined test signal from an analog tape where an attempt has been made to erase that signal. So the first step in this case would be to record a tone or tones and then to make a single pass in the erase mode. If the original signal can be identified, one has demonstrated proof of concept.)
- It seems appropriate to develop an increasingly complex sequential approach to the simulation; for example, begin with an erased modern tape, and, if the concept is proven, move on to more difficult cases, making the simulations available sequentially and in a sequence of increasing difficulty with the last tapes to include portions of sound from the 18½-minute tape.
- As a benchmark, NARA should take measurements of a simulation tape to quantify the amount of erasure, the amount of background noise, and the amount of signal remaining.
- NARA should make preliminary inquires into the operability of the original recording and playback equipment.
- NARA should make a reasonable effort to characterize the tape base and binder of tape 342.
- NARA should review the tape's storage conditions and monitor research related to the best available storage techniques to minimize the possibility of degradation of the original tape.
- When NARA edits and splices tape 342 to remove personal and political sections, the original 18½-minute erased portion of tape should be placed on a separate reel along with those portions of the tape immediately before and after the gap that eventually can be released to the public.
- To stimulate research, NARA should publicize the substance of this discussion in relevant journals and by other mechanisms, making known the availability of the first simulation tape and invite outside vendors to attempt to retrieve what this tape contains.
- NARA should continue to keep up with developments of new methods of analysis of recorded signals.
Permanent members of the committee include: Dr. Norbert Baer, Chairman, and Peter Waters and William K. Wilson. Ad hoc members of the committee are Bruce Koenig from BEK TEK; Dr. James E. Paul from Digital Audio Corporation; John G. McKnight from Magnetic Reference Laboratory; Steve Smolian from Smolian Sound Studios; Jim Ryan from the FBI Engineering Research Facility; and Steven St.Croix from Intelligent Devices, Inc.
For additional PRESS information, please contact the National Archives Public Affairs staff at 301-837-1700 or by email.