From: jrwalliker@gmail.com   
      
   On 10/12/2025 23:06, Don Y wrote:   
   > On 12/10/2025 7:25 AM, Liz Tuddenham wrote:   
   >> Martin Brown <'''newspam'''@nonad.co.uk> wrote:   
   >>   
   >> [...]   
   >>>   
   >>> ISTR that in the Three Mile Island disaster they spent the first fifteen   
   >>> minutes of the emergency trying to silence all the different damn alarms   
   >>> that made it impossible to think in the control room. Only once they had   
   >>> the noise under control could they communicate with each other across   
   >>> the room.   
   >>   
   >> I worked in a university where they had just one sounder for each floor,   
   >> mounted at the end of a each corridor.  They had made it loud enough to   
   >> be heard in the laboratories with all the doors shut.  It would have   
   >> been safer to climb out of a window than enter the corridor and try to   
   >> escape past the sounder.   
   >   
   > You can get 200-300dB klaxon's relatively easily.  I had one in   
   > college that was "fun" (for some perverse definition of "fun")   
   > to play with.   
      
   Are you sure about that?  200dB is a couple of atmospheres.  This   
   would probably be enough to demolish your house.   
   300dB would be apocalyptic.   
   John   
      
   > Also had a large motorized siren out of an old police car.   
   > Amazing how much current it required to spin the mechanism!   
   >   
   >> When it went off one day, nobody could find out what was happening   
   >> because communication was impossible.   
   >   
   > Alarms/alerts should never be "solid" tones.  A cadence makes them   
   > more noticeable AND gives you periods of relief between bursts.   
   >   
   > There's a lot of research on "sirens" for emergency vehicles as,   
   > there, localizing the source of the sound is important.  Observers   
   > need more auditory clues than the naive sirens provide.   
   >   
   > I have three compression driver horns outside the house (to   
   > alert neighbors of a problem) and one inside the house (to alert   
   > occupants).  Driving them with audio amplifiers (instead of fixed   
   > frequency "tuned horns") gives you some variety in how you alert.   
   >   
   > The problem with these things is *testing* them -- especially   
   > "periodically"!   (hence the value of being able to dial back   
   > the SPL)   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)