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Sorry if this is a redundant post, but a quick search didn’t yield anything.

I was wondering if FMOD has the ability to simulate the speed of sound. I have a situation where I have a large stadium in 3D, with virtual PA speakers placed all over the stadium, and would like the announcements on the stadium PA speakers to be appropriately delayed when reaching the listener. The listener can be anywhere at anytime, so the delay has to be able to change dynamically.

Is this something I need to ask our programmer to sort out himself, or does FMOD have this ability already. Or do I set this up in FMOD Designer?

Cheers,
Jeff

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You could try using the Delay DSP effect and set it to 100% wet and use a parameter to set the delay time.

You could drive this with the 3d-distance parameter so that instances of this sound event that are further away would automatically have more delay time on them. There’s a maximum delay time of 5000ms which is approximately 1650m.

You could do the same with a low pass filter to simulate high frequency loss that occurs over distance too.

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Hm we have a time offset effect but we really need a time delay effect (in designer) that way you can just affect the delay period by the distance parameter.

Right now i dont think a DSP effect is a good idea unless it is just for those few sounds. DSP effects add memory and cpu usage, so the programmer would probably be able to implement a small delay based on distance.

Alternatively, you could set up a sound def that is positioned say half way through the layer, then set up a time parameter, which triggers the sound after a while, ie after the parameter reaches the sound def.
Now this would create the same delay every time, but the programmer could set the speed of this parameter based on distance, so that the cursor enters the sound def quicker the closer the source is to the listener.

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Very interesting. Just to add a bit more complexity, how would you suggest simulating Doppler shift of the wave form as it gets farther away?

  • George
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FMOD automatically applies doppler shift to moving sounds, that is what the velocity parameter in set3DAttributes is used for.

-Pete

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Seems to me if fmod is already calculating the volume and 3d position of sounds, it would be a nice option to have it calculate a delay based on the speed of sound automagically too :)

Would be interesting to see if it makes things feel more natural…or if it comes across as laggy/buggy.

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Thanks Pete good to know,

I also agree with nozehed, it would be interesting to see how a calculated delay based on 3D position would affect the sound. Perhaps like a doppler shift on the sound start?

I think it would probably find most use in a game where there was a significant action far away. Combat flight simulators and artillery simulations come to mind.

  • George
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