Soundwaves: Speed of Sound (Delay) & Doppler

Game Engine Game Engine Resources
1

Hi :wave:

If you are looking for eye-candy, you are wrong here. I have been digging through some of my files and found an experiment related to 3D sound in the BGE I want to share. Think of the delay between lightning and thunder introduced by the difference in speed of light and sound. There is also a little siren demo, showing shifted frequency of an amulbance sound while moving.

I think the BGEs actuators don’t do the delay by default. Here we go:

BGE_SoundWave_v2.blend (1012.2 KB)

What it does:

  • on Keys 1,2,3 short soundfiles (gunshots) in different distances at the camera are triggered. An animated sphere shall show the travelling wave. You can observe different delays and different loudness.
  • on Key Left and Right, an ambulance siren moves around. You can observe frequency shift, varying loudness and direction.

grafik
grafik.png3794×1828 863 KB

It should work for moving emitters and listeners as well, as the math is basically just a distance check between two moving points. Maybe this is useful for somebody here.

Please note:

  • I am aware that the speed of sound is not physically correct in there - it’s just a demo.
  • Sound files are from freesound.org if I remember correctly.

Enjoy!

4 Likes
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2

Isn’t aud taking this kind of sound propagation into account already?

3

Hi @wkk

I see some similar parameters in the API, but have never used it.

A test would be quite simple:

  • Place a sound source approx. 340 m from the listener (camera).
  • Play a sound at this location (e.g. gunshot).

If you hear it instantaneously, it doesn’t consider the travelling distance
If you hear it 1 second later, it does.

If someone wants to put this together, fine - it’s really late where I live and I’m out for today

:v:

4

Excellent demo!
Hmmm, I’m really hoping more games go down this route with audio, really helps with immersion.

5

Impressive. There are much to less Sound Demos around for this important Theme. Thank You for sharing.