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October 6, 2011

7

Signal National d’Alert

by soundlandscapes

IT HAPPENS AT NOON on the first Wednesday of every month.  Across Paris, and indeed across most of France, the sonorous tones of the Signal National d’Alert fill the air.

This national alert system or réseau national d’alerte (RNA), comprises a network of around 4,000 sirens across the country operated by France Telecom. The system is designed to alert the public to imminent danger. The characteristics of the alert signal are very precisely defined in a 2007 decree issued by the Ministry of the Interior.

There are in fact two signals, one is the ‘alert’ signal itself (shown above) and the other is’ end of the alert’ signal (shown below).

The ‘alert’ signal consists of three successive cycles with each lasting for 1 minute and 41 seconds and each separated by an interval of 5 seconds. Each cycle consists of five periods, the first of which lasts for 10 seconds with the remaining four periods being 7 seconds long. The ramp-up time for the siren between each period is 1 second and the descent time 4 seconds. The ramp-up time at the beginning of each cycle is 3 seconds and at the end of each cycle the descent time is 40 seconds. The frequency of the siren tone is 380 cycles/second.

The ‘end of alert’ signal is one cycle of continuous signal lasting for 30 seconds.

And so it is, at noon on the first Wednesday of every month this alert system is tested. The signal is varied from month to month so as not to be confused with the actual alert signal but on the first Wednesday of each month it appears in some form.

On the first Wednesday of this month I recorded it from my balcony. The nearest sirens are a long way from my apartment but, despite the wind being in the wrong direction, there it was.  For some reason, in my neck of the woods they ring the church bell at the same time.

Whilst listening to this test alert it occurred to me that if I heard this sound at any time other than the first Wednesday of each month I, like most people I suspect, wouldn’t have a clue what to do or where to go. Let’s hope I never have to find out.

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7 Comments Post a comment
  1. Oct 6 2011

    Every first wednesday of the month I think exactly the same thing. What happens if I hear this at another time? What should I do? Where do I run and hide? Does anybody actually know what to do?

    I recorded the test back in February (see http://audioloungesound.com/blog/2011/02/signal-national-dalerte-paris/ to have a a listen). I also took the recording from my apartment balcony (in the 11th). I actually love the way you get the different sirens overlapping each other, plus with Paris’ tall-building architecture, you also get this amazing reverberation as the sound bounces around the streets.

    Reply
    • Oct 6 2011

      Thanks Colin. I’ve just had a listen to your recording. I find the sirens, especially when heard from a distance, have a rather surreal effect almost like something from a nuclear disaster movie. At some point, I’m going to try to record close to some of the sirens and see what the effect is there. As for what to do and where to go – I shall just follow everyone else I think!

      Reply
      • Oct 7 2011

        Yeah, I’ve been trying to work out where the nearest ones to me are actually situated. As it only happens once a month, it’s not easy to work out!

  2. Oct 7 2011

    Great article and recording. Once upon a time the church bells might have been used for the same purpose as the siren, so I love that you’ve captured them both in the same recording. Maybe as the din of traffic and modern Paris increased it became necessary to turn-up the volume with the introduction of the siren (?).

    Reply
    • Oct 7 2011

      You might be right. Certainly in the UK church bells were used to warn of invasion so it could have been he same here.

      Reply
  3. Oct 7 2011

    I’ve always thought that the best time to invade or attack France would be the first Wednesday of the month just before midday….

    Reply

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