Why do many sirens have cone into air intakes?

[Jim_Ferer]

I wonder if the intake cone serves another purpose.

If you put a sound guide around the stator to direct sound forward, might the sound waves interfere with the free flow of air into the chopper, and might the air flowing (being drawn) into the chopper interfere with the propagation of sound? In other words, the intake cone serves to separate the two flows of air?

[Robert Gift]

Air flow should not affecthe sound propogation.
The sound waves should travel up stream and downstream just fine.

If anything, the rotor cone should help more air get into the
rotor chambers not only by ram air slightly increasing pressure (into the vacuum created by the rotor), but I believe more so by diminishing eddie currents/turbulance impeding air entering the rotor.

I would like to know if it lessens wave cancellation between stator emission and rotor intake emission

FedSig's 2001 is probably the state-of-the-art in efficiency.
All mechanical sirenshould be miniature 2001s.
But the Q's traditionalook would be difficult to break.

All electromechanical vehicle sirenshould be replaced by electronic.
(Mechanical sirens should be relegated to parades and show vehicles.)

Electronic sirens allow voice instruction, instant silence, different sirens tones, and high volume output at lower frequencies.
(Mechanical sirens emit highest dB only atheir highest frequencies.
But lower tones carry farther and penetrate vehicles better.)

Electronic sirens also use much less electrical power and weigh much less.

Face siren speakers forward for traveling down streets and one speaker aimed left and one right for intersections.
As you near intersections, press a momentary contact button to switch power from front speakers to side-facing speakers.
This will concentrate sound where needed and less elsewhere.

[Is that a -20 coming?]