So how much musical design / composition goes into the creation of those annoying “rooOooOooooo… wah wah wah wah… roooOooooooooo WaaOAO WAAoooWAooo waaooooo” sirens? Is there some composer sitting down and thinking, “OK, I’m going to write the most beautiful melody I can, and then make the complete opposite of that”? Or some acoustic engineer messing with dissonance and doppler effects to fine-tune the most grating frequencies imaginable?
Do they do a lot of pre-release testing, rounding of hapless volunteers and subjecting them to hours of acoustic trauma to find out what breaks people the best?
I have heard that the musical interval of a “tritone” is used in police sirens, maybe the French ones.
A tritone “devil’s interval” is three whole steps. In the C major scale it is the interval between F and B, play it on your favourite musical instrument and it will sound very edgy, and it just screams to resolve to E and C.
Sirens used to be a completely mechanical affair. A crank (motorized or hand) turned a fan which forced air thru the whistlers.
The original two tone sound to sirens was caused by the doppler effect of the rotation of it. Usually, most of the sound came out of one side, so the whole siren rotated for 360° spread. High and loud when it was pointed toward you; low and softer when away.
Today’s sirens are electronic affairs, often made of multiple sounds coming from multiple speakers pointed in multiple directions. There’s also a whole field of attention getting acoustics that has grown up around the biz.
I think the challenge in all of these warning sirens is to have them sound distinctly different than anything else normally heard, and also be very attention-getting. The fact that the sound is aggravating is the same principle as the annoyance of a baby’s crying – it is SUPPOSED to get your attention. Different places seem to like using different sounds, most notably the differences between Europe and North America, but all serve the same purpose. In some places police cars are also equipped with horns that make a unique sound unlike any car or truck, but I don’t think this is common or particularly useful since they can just momentarily activate their sirens.
I also discovered some time ago that fire trucks around here are also equipped with super-loud PA systems. This is in case they are behind some moron who feels that just because the traffic is congested and they have no immediately obviously place to pull over, they can just sit there and ignore the siren immediately behind them. That’s when the fire truck suddenly blared “Get out of the way – NOW!” loudly enough to rattle nearby windows, and magically, someone made a space for them in the next lane and they vanished into it.
My shop is within eyesight of the firestation. So I get to hear them pull out on a pretty regular basis.
The siren is more or less normal, I think, but the horns are something else. When they get to the intersection up the way a bit, they will lay on the horn, and it’s hard to describe, but even from pretty far away and with it facing away, it’s pretty attention getting.
That reminds me that when my son was very little we got him a wonderful toy fire truck that I freely admit I enjoyed playing with myself! It was maybe 18 inches or so long and nicely detailed, complete with realistic flashing lights, but the coolest thing about it was the diesel engine sounds, siren, and horn. According to the packaging, those sounds were high-def recordings of an actual fire truck, and they were rendered with amazing accuracy whenever you pushed the desired buttons or switch. Now that’s what I call a good use of technology as applied to toys!
My two oldest boys got those for christmas one year. Gma was so excited for them to go home with us…my nephews play with them now. They’re cool yes, but a terrible gift idea
It was maybe 18 inches or so long and nicely detailed, complete with realistic flashing lights, but the coolest thing about it was the diesel engine sounds, siren, and horn. According to the packaging, those sounds were high-def recordings of an actual fire truck, and they were rendered with amazing accuracy whenever you pushed the desired buttons or switch. Now that’s what I call a good use of technology as applied to toys!