How would a UK siren sound for Tornado Warnings?

[Robert Gift]

Theoretically, the wider a port, the lower the pitch would be.

So if I were to take a double-ended, 8-port Sentry, which have long ports, and slice off half of one rotor to make the ports shorter, there would be some dissonance between the rotors?

No. You know it would be the same pitch.
The narrower stator ports would release less air so less dB, but the pitch would be the same.

[SirenMadness]

Let's explain it this way: if the rotors are different in width, but both spun by the same type of motor, there would be a difference between their sounds, though not such a big one. If you were to compare an STH-10 with a much smaller twelve-port siren spun by the same type of motor, to achieve the same speed as the rotor of the STH-10, you will find that, besides a smaller sound volume, the pitch of the smaller siren will be different from the STH-10.

[SirenMadness]

Theoretically, the wider a port, the lower the pitch would be.

So if I were to take a double-ended, 8-port Sentry, which have long ports, and slice off half of one rotor to make the ports shorter, there would be some dissonance between the rotors?

I think that you're referring to the axis of height. I was referring to the difference in width; the height of a port, along with its width, determines the volume, while the width also determines the pitch.

[Daniel]

Theoretically, the wider a port, the lower the pitch would be.

I think that you're referring to the axis of height. I was referring to the difference in width; the height of a port, along with its width, determines the volume, while the width also determines the pitch.

As far as I know, the only thing that determines pitch is the number of times per second that the air is chopped. This is determined by the number of ports on the rotor and motor speed. One could make an 8-port siren with a rotor that was 1m. in diameter and 10 cm. tall, and the pitch would be exactly the same as an 8-port siren that was 50 cm. in diameter and 30 cm. tall. The first siren would have much wider ports than the second one, but they both still have eight ports.

[SirenMadness]

If the ports are bigger, wouldn't it take more time for a chop to be completed?

[Robert Gift]

Yes. The dimensions of the ports will affect harmonic content (waveforms).
I presume the narrower the ports, the more higher frequencies in the waveform.
The larger (fatter) the ports, the less higher frequencies in the tone.
But I do not know. Would be fun to try all kinds of ratios.
Would be nice to know the research that Federal Signal performed to come up with the idea ratio.
For example, why did they make the 2t22 10/12 instead of 5/6, which would create a tone an octave lower which presumably travels farther?

[SirenMadness]

Another reason for putting a ten-to-twelve ratio of ports on the 2T22 and 3T 22 instead of a Model 2 is that a Model 2 will only accommodate such an optimal number of ports which does not make it more complex to build. I think that the 2T22 and 3T22 were built with the sound properties that they were built with was because the Civil Defense organization then made the use of that specific sound type important, and the same ratio of ports as on a Model 2, on a 2T22, would be kind-of low.