# FMOD for Unreal, Occlusion returns only 0 or 1, is no intermediate values is expected behaviour?

**URL:** https://qa.fmod.com/t/fmod-for-unreal-occlusion-returns-only-0-or-1-is-no-intermediate-values-is-expected-behaviour/23765
**Category:** FMOD Studio
**Created:** [December 4, 2025, 4:48pm UTC](https://qa.fmod.com/t/fmod-for-unreal-occlusion-returns-only-0-or-1-is-no-intermediate-values-is-expected-behaviour/23765 "2025-12-04T16:48:18Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![JoeChip](https://avatars.discourse-cdn.com/v4/letter/j/e79b87/32.png) [@JoeChip](https://qa.fmod.com/u/JoeChip)
#### Post date: [December 4, 2025, 4:48pm UTC](https://qa.fmod.com/t/fmod-for-unreal-occlusion-returns-only-0-or-1-is-no-intermediate-values-is-expected-behaviour/23765/1 "2025-12-04T16:48:18Z")

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Hi,  
I’m testing the Occlusion system in FMOD for Unreal and I would like to confirm whether the current behavior is correct or if I’m missing something in the setup.

I followed the official documentation:

- Created a continuous parameter in FMOD (0–1) named exactly as the “Occlusion Parameter” in the plugin settings.

- Automated a low-pass filter in FMOD so that the parameter value controls frequency cutoff (0 = 20 kHz, 1 = 20 Hz).

- Enabled Occlusion on the FMOD Audio Component in Unreal (Occlusion Trace Channel set to Visibility, tested also with complex collision).

- The parameter is local (instance parameter).

**The issue:**  
When moving the listener around a test map, the occlusion parameter only receives values **0 or 1**.  
There are no intermediate values such as 0.2, 0.5, 0.7 etc.  
Even when the sound source is only partially obscured by geometry, the value jumps straight from 0 to 1.

I’ve tested multiple collision settings and trace channels, but the behavior is always binary.

**My question:**  
Is this the intended design of FMOD for Unreal occlusion (single line trace → 0 or 1)?  
Or should the FMOD integration provide continuous occlusion values by default?

I want to confirm whether the plugin is working correctly, or if continuous occlusion requires implementing a custom solution (e.g., multiple raycasts and setting the parameter manually).

Using FMOD Studio 2.03.10 and UE 5.4 Thanks in advance for clarification!

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<div class="post-metadata">

### Author: ![li\_fmod](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/li_fmod/32/6577_2.png) [@li\_fmod](https://qa.fmod.com/u/li_fmod)
#### Post date: [December 11, 2025, 12:06am UTC](https://qa.fmod.com/t/fmod-for-unreal-occlusion-returns-only-0-or-1-is-no-intermediate-values-is-expected-behaviour/23765/2 "2025-12-11T00:06:37Z")

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Hi,

Thank you for sharing the information!

> [@JoeChip](#):
>
> Is this the intended design of FMOD for Unreal occlusion (single line trace → 0 or 1)?  
> Or should the FMOD integration provide continuous occlusion values by default?

Yes, the behaviour you are seeing (the parameter switching only between 0 and 1) is the intended design of the current FMOD Unreal plugin.

> [@JoeChip](#):
>
> I want to confirm whether the plugin is working correctly, or if continuous occlusion requires implementing a custom solution (e.g., multiple raycasts and setting the parameter manually).

Your setup sounds correct to me.

If you require continuous occlusion values, you might need to implement a custom solution on the Unreal side.

For sound design ideas on enhancing the perception of occlusion, this related post may offer some general ideas: [How to create illusion of source occlusion with reverb](https://qa.fmod.com/t/how-to-create-illusion-of-source-occlusion-with-reverb/23753)

Hope this helps!