Via the BB Submitterator, Boing Boing reader Pea Hix says,

"This is an excerpt from a recording I found on an old wire spool (pre magnetic tape recording medium). On April 23rd, 1950, a New Jersey man by the name of Fred Weber was setting his wire recorder up to record a phone conversation, and to test the signal he called the local Time Bureau. On the surface this would appear to be a rather mundane recording, but it isn't until you hear the time lady sneeze that you realize – this is a LIVE person reading off the time in 15-second intervals! "

Video link, and there are links to more recordings of this kind here in the video description on YouTube.