Here's a headline that you might have seen before: "Gunshot tape that could solve the JFK mystery." It's back (in today's Guardian), and so is the once-famous Dictaphone belt from Dallas.
The day JFK was shot, a motorcycle cop's mike was stuck open, and the sounds it picked up in or around Dealey Plaza were recorded on the belt. There's all kind of stuff on it, including what may be gunshots and/or static bursts. A sophisticated 1979 House investigation decided that the belt contained evidence of a fourth gunshot, and concluded that a second gunman had to have acted.
That conclusion was later called into question by, of all things, a Penthouse magazine stunt. As a marketing ploy, Penthouse stapled a cheap recording of the belt's contents into one of its issues, and a Penthouse reader eventually noticed some chatter on the recording that called into question the timing scheme used by the House analysts. Defenders of the scientists responded with various technical explanations to account for the apparent anomaly, but the matter has never been resolved.
Cut to 2004. The Guardian reports that "Scientists at the Lawrence Berkeley National Laboratory have begun work on a digital scanning apparatus" that may yet reveal the tape's secrets, if any. Gary Mack of the Sixth Floor Museum in Dallas told the paper that "with today's technology, we can get a better reading and answer the question, one way or the other." You may have seen a quote just like that one before, too.