---
title: occlusion
framework: avfaudio
role: symbol
role_heading: Instance Property
path: avfaudio/avaudio3dmixing/occlusion
---

# occlusion

A value that simulates filtering of the direct and reverb paths of sound due to an obstacle.

## Declaration

```swift
var occlusion: Float { get set }
```

## Discussion

Discussion The value of obstruction is in decibels. The system blocks the direct and reverb paths of sound between the source and listener. The default value is 0.0, and the range of valid values is -100 to 0. Only the AVAudioEnvironmentNode class implements this property.

## See Also

### Getting the 3D Mixing Parameters

- [obstruction](avfaudio/avaudio3dmixing/obstruction.md)
- [position](avfaudio/avaudio3dmixing/position.md)
- [rate](avfaudio/avaudio3dmixing/rate.md)
- [pointSourceInHeadMode](avfaudio/avaudio3dmixing/pointsourceinheadmode.md)
- [reverbBlend](avfaudio/avaudio3dmixing/reverbblend.md)
- [sourceMode](avfaudio/avaudio3dmixing/sourcemode.md)