A modern look at the buzzes and clicks on the Watergate tape reveals new information on the perpetrators of the tape erasure and their motives.

Watergate, the greatest political scandal of the 20th century, remains shrouded in mystery, in part, due to an 18½-minute gap in the tape recording of a Watergate discussion between President Richard Nixon and his chief of staff Bob Haldeman. Despite many attempts to recover its contents, unlocking the secrets of the gap has, until now, remained beyond the realm of possibility. This article documents forensic breakthroughs in understanding the “18½-minute gap.”

Watergate Conversation on June 20, 1972
Early in the morning of June 17, 1972, five men were arrested at the Watergate headquarters of the Democratic National Committee. The men were eventually linked to Nixon’s re-election campaign.At the time of the arrests,Nixon and his chief of staff were enjoying a weekend getaway at Key Biscayne, Florida, before returning to the White House on Tuesday, June 20, to assess the damage from the arrests. Meeting that morning at 11:30, Nixon and Haldeman discussed the Watergate situation. A secret White House taping system installed at Nixon’s orders recorded the entire 69-minute conversation. Some 17 months later, as investigators searched for Watergate–White House connections, the 18½ minute Watergate portion of the Nixon–Haldeman conversation was found to be completely obliterated.

Nixon’s loyal secretary, Rose Mary Woods, admitted to mistakenly making a single erasure of 4½ to 5minutes on the tape while making a phone call but vehemently denied making the entire 18½-minute erasure. Woods later conceded that she may have erased between 5½ and 6minutes of the tape, but nomore. All that remained of the 18½-minute discussion was a sequence of clicks, pops, and buzzing sounds. Little of the situation made any sense. Why would Woods admit to making a portion of the erasures but deny making the remainder? Why not claim the entire erasure was an accident? And what caused all of the strange sounds remaining on the tape?

1974 Advisory Panel Report on the Tape Gap
Upon discovery of the tape gap in November 1973, an advisory panel of scientists convened to assess the condition of the tape. After months of analysis, the panel issued a report¹ that concluded that the 18½-minute gap was composed of five to nine erasures made with Woods’Uher-5000 tape recorder. Woods’ tape recorder was found to have a faulty bridge rectifier that served to convert the AC power to DC, when this component failed during testing it was replaced and the faulty component was tossed in the trash—a critical error. The report left many questions unanswered. The panel was unable to explain or reproduce the erasures’ buzz sounds, was unable to explain the loud-soft-loud buzz sequence across the erasures, and was unable to correlate the magnetic marks left on the tape to Woods’ admitted erasure accident.

Figure 1 is the summary diagram excerpted from the 1974 Advisory Panel Report. As shown, the erasure consists of an initial loud-buzz segment, then a longer soft-buzz segment, and finally another loud-buzz segment. Interspersed between some of the erasures are short un-erased segments lasting only seconds each. In the middle of the third erasure the buzz transitions from a loud-buzz to a soft-buzz. In a technical note to the report, the decrease in the buzz level is attributed to unexplained “transient noise.”Curiously, the length of the initial loud-buzz segment precisely matched Woods’ admission to erasing 4½t o 5 minutes of the tape. However, according to the panel scientists, the third erasure does not end with the transient noise but instead continues on for more than five minutes of soft buzz.