Allan Friswell's comment (scroll down) on this video for "O Superman" for Laurie Anderson contends:

The UK nuclear power stations of the 80s had that "ha" sound on continuously 24/7. Apparently it got so you stopped hearing it, and only when it STOPPED did you know there was an emergency. Apparently you heard the silence quicker than if it were an audible alarm.

(the song features a soft "ha" looping continuously in the background). This has some serious poetic heft, so I want to believe it, but I also don't trust it for the same reasons.

Can anyone confirm or deny?


Yes they absolutely did.

I know this because I've been in several of them. However it was only in the most dangerous places - the criticality labs, where there was enough nuclear materials that, if mishandled, they could generate a fatal radiation dose in a matter of seconds. Most nuclear power stations would not have had a criticality lab and hence not an alarm of this kind. Only places like a research establishment (where I heard them) or a fuel rod assembly facility would have had them.

The sound was a short electronic bip every few seconds, not a 'ha' or anything else that could be mistaken for a human voice. I suppose different places may have used different sounds, but the ones I visited were all the same. They were called 'confidence tones'.

The sound played 24/7 to indicate that everything was OK, and especially that the alarm system was functioning normally. The sound stopping indicated a problem with the alarm. I'm not clear if the the noise stopping was treated as an alarm - or what level of alarm.

I was only ever a visitor, but I was told by the people who worked there regularly that you got used to it quickly and really noticed if it stopped.


  • 8
    This answer didn't make any sense until I read the references. If something kills you within seconds and there's a bip "every few seconds", there's enough time to kill you between the bips. The article clarifies that there is also a loud warning if something happens. That makes the quote in the question nonsense: "you heard the silence quicker". Silence of the bips just tells you that the alarm is broken. – pipe May 25 '19 at 23:04
  • 1
    You can hear it in this video, starting about 6 minutes in. youtube.com/watch?v=A6mpz7FcCTU – Paul Johnson May 26 '19 at 19:04
  • @pipe if the sound stops, maybe someone dies but other people can take action to prevent worse from happening. The goal of such systems isn't to prevent accidents but to limit their scope and impact. – jwenting May 27 '19 at 5:55
  • 3
    @jwenting That's a possible side effect, but the articles are clear that the constant sound is to make sure that the warning system works, not to signal that there is a danger. – pipe May 27 '19 at 7:01
  • 3
    I think the answer should include that the claim is pretty grossly misleading about the purpose of the sound and that it did not "indicate emergency by stopping it". The sources state quite clearly that the beep sound signals that the warning system is working and that in case of an emergency there is an additional alarm immediately. – redleo85 May 27 '19 at 17:08

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .