Need help with Gverb -- Making a Siren Effect

Hello community,

Chad here, I’m in a bit of a situation right now…

I’m currently a developer for a modification that I’m working on, it’s for an emergency first responders based game, and right now I’m trying to make a few realistic sounding sirens, but i have one problem - i do not want to record off youtube because the recorded audio clip would be all distorted and statics in the background, so i found the stock siren tones from the actual manufacturing site, Whelen Sirens, but they are computer generated, so when you play it, it doesn’t sound real but fake, because of no “air”.

I just learned about Gverb last week and been playing with the settings ever since to accomplish a realistic sounding siren…i want my audio to sound like that it’s blaring out from the siren speaker, with the behaviors like pitch, echo, etc…

The game’s camera view is aerial view, and it’s taking place in a downtown setting, so i would like my sirens to sound like it’s blaring through the downtown street, echoing and loud, as if the tones are bouncing off the buildings, etc, but i understand that the possibility of achieving this kind of setting may be thin, but if anybody here knows a gverb settings that would accomplish this level of realism…

example -

I’m sorry about my grammar, it’s not so good, but i hope you understood most of it, or at least the objective…

Thanks and hope to see some positive responses!

I can’t really help you with the gverb settings, but you might also want to have a look at other free reverb plugins. Many of them are listed in this thread:

Thanks, dude. I checked out that topic and I think the " Tap Reverberator" might be my best option.

If the siren is moving relative to the listener, (like in those Youtube clips), there is Doppler shift in the frequency as the vehicle passes, e.g.

the equalization also changes as the vehicle approaches, more higher frequency content the closer it gets

Gverb (nor any reverb) will not add Doppler shift, or alter the equalization with time.

The Doppler effect would do the justice for me. but I assume that there are no plug-ins of this effect available for free, right? I checked google and no luck.

Edit : never mind, I just found a possible one, need to check if it compatible with audacity. It’s called “ADopplerEn2”

You can create a Doppler effect using the “Sliding Time Scale/Pitch Shift” effect (included in Audacity 1.3.13).
It’s a little bit cumbersome to do as you will need to process the audio in sections.
The “coming toward you” section needs the pitch to be shifted up a little and the speed (Tempo) increased by the same %.
The “going away from you” needs the pitch to be lowered a little and the tempo slowed down.
Make a note of the settings that you use for these two sections as you will need them for the next section:
The “going past you” section needs to “slide” from the quicker/higher settings to the slower/lower settings.

As well as the Doppler effect you need the volume to gradually increase as the siren approaches, and reduce as it goes away - use the “Envelope Tool” or “Fade” effects for this.

If you use the Envelope tool you will need to “Render” the track before adding Reverb (Tracks menu > Mix and Render).

To produce a realistically changing reverb, make a duplicate of the track (Ctrl+D) and apply the reverb to the duplicate track. You will then need to “shape” the volume of each track so that the distant siren has relatively more reverb than the close siren. When the siren is very close the duplicate (reverb) track should probably be silent (or relatively low) so that you have only (or mostly) the direct (dry) siren sound.

In addition to the previously mentioned reverbs, there’s a new one here:

Hey, guys,

I’m back with a new question related to my siren editing project; After learning how to apply Doppler and environmental effect to my siren tones, i am still faced with a conflicting issue that prevents me from releasing the sirens to the public…

How can i make my siren tones sound electronic? In real life, the sirens emits out of an 100 + watts Electric speaker and the tones i currently have are online generic tones, meaning they aren’t recorded in real life but computer generated from the manufacturing company that posts their siren tones for public viewing on their website. So because of this, i can’t have my wail to start off like this ( in the beginning of the video, where the cop chirps his wail momentarily at the intersection)

I tried doing the telephone/leveler effect but no avail. Any help is appreciated.

This link shows you my wail tone in question for comparison. You’ll hear the Doppler and echo effects that i applied. But doesn’t sound quite life-like to me personally.

I do not quite understand what do you want to achieve.
You write that the game is from an aerial view, isn’t it?
If so, it all depends on how high the view is.
The higher the position, the more high frequencies are attenuated (air absorbtion) and so are the echoes (maybe even more, since the high freqs are thrown back in different directions by the walls). The doppler effect is also not very prominent since the distance doesn’t change very much in comparison.
Furthermore, the signals amplitude will greatly be influenced by the cars position such as

  • open field
  • between large buildings (strongest reflection)
  • shadowed by woods, buildings etc.

There’s no limit for the complexity of physical modelling your sound.
The realism depends on how much the sound can be altered during game play.Or is the whole sfx layout built on prerecorded without any filtering possibility?
What were your intentions when you’ve applied the telephone and leveler effects? They seem to me totally different, but you had surely a general purpose in mind.
Maybe you can improve the sound by applying a amplifier/cabinet emulation that reproduces actual physical speaker responses.
Sorry, I am afraid, this wasn’t of much help to you.

Is this the sort of thing you’re after?

I made a duplicate copy of your siren sound, then use the Equalization effect to roll-off some of the treble on both the original and duplicate tracks, but more so on the duplicate. Then applied this “Pseudo Stereo” effect to the duplicate followed by GVerb (just shortening the reverb time to about 2.5 seconds and reducing the early reflections a little.
Then I added another track with some “traffic sounds” (downloaded from and mixed the three tracks together (using the track Gain sliders to set the levels).