by cri_oguchiComment Closed

CRI ADX(Unreal Engine) v1
Beginner 09 Sounds heard from behind a wall

Sounds can be heard from behind a wall

Even if there is a wall between you and a sound source, you will still be able to hear that sound, although it will be muffled.
This effect is called "occlusion" and this is what we will simulate in this tutorial.

Before starting

To avoid any confusion, please remove the sound that you placed on the level during the previous tutorial, "Beginner's Guide 08 Playing 3D Sound (2)."

Placing walls and sounds

First, let's place some cubic static meshes to create the walls.



Place the "SimpleMusicAcb_simple_bgm_Cue" cue on the opposite side of the wall from the player.

Make sure that "SimpleMusicAcb_simple_bgm_Cue" does not come into contact with the wall or floor.
Just like in the previous tutorial, configure “SimpleMusicAcb_simple_bgm_Cue” as a 3D sound.

Setup of the occlusion effect

Select "SimpleMusicAcb_simple_bgm_Cue" and look at the "Attenuation (Occlusion)" section in the details window.

  • Check "Enable Occlusion".
  • Set "Occlusion Low Pass Filter Frequency" to 10000.0.
  • Set "Occlusion Volume Attenuation" to 0.5.

We will explain these settings in more details later.

Listen to the sound

Start the game. You will hear muffled sounds whenever there is a wall between the camera and the sound source.
However, if you move around the wall and there is an unobstructed line of sight between the camera and the sound source, the sound will be clear.

With the current settings, the sound is heard from the camera's position.
This is because the listener object is located on the camera.
This can sound a bit unnatural if you're trying to hear the sound coming from the character's position.
This problem will be solved in the next tutorial.

About the settings

"Occlusion Low Pass Filter Frequency"

The smaller this value, the more muffled (i.e., filtered) the sound will be.

"Occlusion Volume Attenuation"

Specifies the volume multiplier when there is a wall between the listener and the sound source.

"Occlusion Interpolation Time"

This is the amount of time it takes for the sound to become muffled when an object blocks the path between the listener and the sound source.
This is also the time it takes to return to a clear sound when there is no longer an object between the listener and the sound source.


Tips

What is a listener?

This term describes where in the game space you are listening to the sound.

If you always hear only muffled sounds

If the sound source is embedded in the wall or floor, the sound will always be muffled.
Therefore, if this happens, check the position of the sound source.