My favorite radio show, the Regular Guys in Atlanta, has mentioned the need to “build back up” their 7-second delay after a caller has said something profane that needed to be dumped. This pretty much has only come up during their “make the Regular Guys laugh” contests, in which callers call in with jokes and try to get one of the Regular Guys to laugh, and naturally an occasional joke is inappropriate and has to be dumped. Several years ago, I remember Larry saying they needed to go to commercial break to build their delay back up, but I think even then (the early 2000’s) it wasn’t necessary to go to commercial break to build the delay back up, just more convenient. Eventide, Inc. has long produced a “dump box” that automatically extends the natural pauses in speech by fractions of a second in order to get the radio broadcast (that we all hear) back to 7 seconds behind the live version (being spoken in the studio). I thought this was fascinating, so here’s how it works:
The show is being spoken by the hosts and callers at “live” time, but we hear it on the radio 7 seconds later. A caller says something profane, and one person working the dump button presses it, and the entire previous 7 seconds is skipped in the broadcast version. This means that 6+ seconds of acceptable speech and one or two words of inappropriate speech are just skipped; as far as the listener is concerned, they never happened. This is usually very noticeable. The radio show will abruptly go from a caller speaking to the host speaking (or laughing, or groaning) in a disjointed manner, possibly with an explanation and possibly without.
The host(s) will then be broadcasting completely live, with no delay between their speaking it and your hearing it, except as entailed by the speed of light. They can’t risk putting any more callers on the air for a minute or two, and they have to be careful not to cuss while the delay gets built back up.
The way the delay gets built back up is that their fancy computerized machinery automatically detects the short pauses in between words and sentences, when no voice is speaking, and extends them by fractions of a second in the broadcast version that we hear. It is imperceptible because no voice is slowed down or lower or otherwise weird-sounding. After a minute or two of harmless banter, the extended pauses in the broadcast version have added up to 6 or 7 seconds again, and the broadcast version is now sufficiently far behind the live version.
Another option to imperceptibly build the delay back up is to extend the commercial break by a few seconds here and a few seconds there, so that a 30-second commercial becomes 31 seconds or a 58-second commercial becomes 60 seconds in the broadcast version but not in the live studio version. Actually, with a show with long commercial breaks like the Regular Guys, each commercial only need be extended by a half-second or less.
A third option I’ve read about is much more low-tech: 7 seconds before the commercial break ends in the studio, the host starts speaking to welcome the listeners back to the show, and this is stored in the buffer somehow (maybe the same or maybe different equipment from above) and only played after the commercial ends, so when the listeners hear it, the broadcast is now 7 seconds behind the live version.
seven second delay, Straight Dope message board
Radio Broadcasts, Delay, and Naughty Words, Straight Dope message boards
Computerized broadcast delay
Eventide, Inc.’s Wikipedia article (specifically the timeline of noteworthy products)