How to create a realistic "drive by" siren sound?

Hello :)!
I wanna create a realistic siren sound inside the unreal engine. I have my Police Siren SFX and imported it to the ue4. It sounds create but a little bit unrealistic.

So for example: When you hear the police siren it sounds like you are in front of the car and thats nice but in real life, when the police car drives away siren sound is darker then when you are in front of the vehicle. I do not really know how i can describe it, so just look at this video and you will understand what i mean: => At the 5. second you hear the default police siren SFX, but when the car drives away at the 8. second, you hear the same siren but its darker and i dont know…
Another good example: (19. Second) you can hear the default siren and then the same but darker version when it drives away

Does anyone know how to simulate this effect in the unreal engine? :o


What you are looking for is an effect called the Doppler effect. The effect changes the sound in a few different ways including pitch and volume.

I’m relatively new at programming within UE4 so I won’t be much help there. I did find this link from a quick google search though. Maybe it can be of help.

No, you’ll want to use the Simple Delay Source Effect for this. The phenomenon you’re describing is called Doppler, the Sound Cue node of the same name is just a pitch modulator. The Simple Delay Source Effect, however, simulates doppler by adjusting the delay from the source to the listener according to the speed of sound. Moving around creates a natural and realistic doppler effect. You can tweak the results by adjusting the Speed of Sound depending on your worlds’ scope and physics. (Normally one U Unit = a cm)


First of all thanks for your answers :)!
I ask this already in Discord but where do I find this feature? Iam using the 4.21.2, do i have to upgrade my Project? :confused:
(If i get a answer first in Discord i add the answer to this questions to this post for other people who maybe search the same feature :slight_smile: )

Dannthr (Dannthr#0899) answered it on discord :slight_smile: Thx ^^
“To access Source Effects, you need to turn on the Unreal Audio Engine