Creative warning system!

[Mathew Bailey]

An idea is to attach a siren chopper to an elevator motor/generator set but you would need to add extensions to the rotor/armature shaft.
Most elevator motor generators spin at 1800 rpm so making the rotor ports smaller in order to increase the number of ports for a decent pitch.
Another idea would be installing one or more 1003's on a ship using a rheostat or variable transformer for a low tone blast.

[Robert Gift]

I would prefer the lower tone, which would travel farther than a higher tone.
I wonder why siren manufacturers don't make lower toned (fewer port)
sirens.

[SirenMadness]

While a low pitch does make a siren generally better, a pitch that is way low will need allot of energy from the siren's motor to make it very loud at a shorter distance.

[Trey]

I would assume that 6000 dB could be heard pretty well around the world (calm weather permitting). I mean Krakatoah wasn't that loud and you could hear it in places like Japan and China.

[Robert Gift]

The sound pressure wave from the blast circled the earth several times!

[JasonC]

The atmospheric decibel limit is around 194dB, which means anything more would have to travel through a different medium (ground, water, etc.) or become a shock wave. They measure the decibel level 100 feet in front of the siren because it's an outdoor warning siren and more accurate coverage ratings can be generated from that. Decibel levels right in front of a siren can range form 140-170ish.

Actually, a higher tone carries further than a low tone, however, a low tone penetrates better and is more easily heard.

[Robert Gift]

Interesting! Thanks Jason.
I had wondered with the atmospheric limit was.

But I am curious about the claim that higher frequencies travel farther.
Do you know of any studies?

I have noticed that we will first hear the lower descending sweep of a distant electronic siren before we can detect any other part of the sweep
pattern. As the siren gets closer, we are then able to hear the whole sweep.

[JasonC]

Interesting! Thanks Jason.
I had wondered with the atmospheric limit was.

But I am curious about the claim that higher frequencies travel farther.
Do you know of any studies?

I have noticed that we will first hear the lower descending sweep of a distant electronic siren before we can detect any other part of the sweep
pattern. As the siren gets closer, we are then able to hear the whole sweep.

You hear the lower tone first because your ear can pick up that tone much more easily than a high pitched tone. But yes, higher pitched sounds do travel further. (Sentry Siren uses this principal in their dual tone sirens) For example, a 1,000Hz sound wave at 100 watts of power will travel much further than a 100Hz sound wave also at 100 watts of power. It also takes much more energy to make the 100Hz the same decibel level as the 1,000Hz tone. Hence, this is why a 100w police siren can be heard from a mile away easily while a 100w subwoofer is considered a very paltry room/car sub. I forget the exact scientific explanation, but if I feel like looking it up I'll post it here.

[Robert Gift]

You hear the lower tone first because your ear can pick up that tone much more easily than a high pitched tone.

The higher frequencies are not that high (and I'm not THAT old!!) that they are any more difficult to hear.
But I wonder if this is a characteristic of the vehicle siren speakers putting out more dB at the lower part of the sweep cycle.

But yes, higher pitched sounds do travel further. (Sentry Siren uses this principal in their dual tone sirens) For example, a 1,000Hz sound wave at 100 watts of power will travel much further than a 100Hz sound wave also at 100 watts of power. It also takes much more energy to make the 100Hz the same decibel level as the 1,000Hz tone.

Yes, I can understand that.

Hence, this is why a 100w police siren can be heard from a mile away easily while a 100w subwoofer is considered a very paltry room/car sub. I forget the exact scientific explanation, but if I feel like looking it up I'll post it here.

I'd love to read anything you have. Thanks, Jason

[StonedChipmunk]

Hence, this is why a 100w police siren can be heard from a mile away easily while a 100w subwoofer is considered a very paltry room/car sub. I forget the exact scientific explanation, but if I feel like looking it up I'll post it here.

I seriously doubt that any 100w police siren could be heard a mile away. Even most electronic outdoor sirens can't be heard that far away.