Spatializer

The atmoky Spatializer is a plug-in which can be used in Sound Attenuations to spatialize audio (e.g. Sound Cues) in Unreal Engine. The plug-in renders audio objects in 3D space and outputs them either binaurally for headphone playback or in stereo for speaker playback. It features a variety of parameters to control the spatialization, such as source width, occlusion, directivity, and near-field effects.

If you want to spatialize audio directly within MetaSound nodes, check out the MetaSound version of the Spatializer.

Usage

Set Platform Spatializer

In the Project Settings, navigate to the Platforms settings for each platform you are targeting and set the Spatialization Plugin to atmokyTrueSpatial Spatializer.

Create Spatializer Settings

Create a new atmoky Spatializer Settings asset by right-clicking in the Content Browser and navigating to “Audio / atmoky” and select atmoky Spatializer Settings. For more information about the settings, refer to the Spatializer documentation.

Create Sound Attenuation

Create a new Sound Attenuation asset by right-clicking in the Content Browser and navigating to “Audio / Sound Attenuation”. Open the Sound Attenuation asset by double-clicking it, and perform the following steps:

check the Enable Spatialization box
set the Spatialization Method to Binaural
add the atmoky Spatializer Settings asset you created to the Spatialization Plugin Settings field

Apply to Sound Cues or MetaSound Sources

You can now use the Sound Attenuation asset in your Sound Cues or MetaSound Sources by setting their Attenuation Settings to the Sound Attenuation asset you created.

Spatializer Settings

Output Format

With the Output Format parameter you can select between different output formats for the spatialized audio signal. The available options are:

Binaural: HRTF-based binaural rendering for headphone playback
Stereo: Stereo rendering for speaker/headphone playback

Stereo width

The stereo width of the rendered audio. The value ranges from 0% to 100%. With 0% the left and right input channels are mixed to mono before spatialization, and with 100% the left and right input channels are kept separate.

This setting currently only affects the binaural output format.

Occlusion

Value driving the occlusion processor simulating a sound source being occluded by an obstacle. The value ranges from 0% to 100%, where 0% means no occlusion and 100% means full occlusion.

Directivity

The directivity settings describe how the sound is radiated into space. The directivity pattern is defined by the inner and outer angles, outer gain, and outer low-pass setting.

The Inner Angle defines the angular spread around the frontal direction where sound is emitted without attenuation. The Outer Angle defines the angular spread around the frontal direction outside of which sound is attenuated according to the Outer Gain and Outer Low-Pass parameters. In between the inner and the outer angle, the attenuation is linearly interpolated / blended.

The Outer Gain is a value in Decibels between -80dB and 0dB, where 0dB that the sound is not attenuated at all. The Outer Low-Pass is a value between 0% and 100% controlling the intensity of the low-pass filter, where 0% means that the sound is not filtered at all and 1000% means that the sound is completely filtered.

Nearfield Effects

When sources are far away from the listener, the binaural cues (i.e. the interaural time- and level differences) are almost independent of the source distance. However, when sources are close to the listener, the binaural cues are strongly dependent on the source distance. This is the reason why very close sources, such as the sound of a voice whispering in our ear, sound very distinct and evoke a special feeling of intimacy. More precisely, the lower frequencies of close sources are amplified, the interaural level differences are increased, and the sound color for each individual ear changes due to the parallax effect.

The following parameters can be adjusted:

Start Distance: defines the distance at which the near-field effects start to to kick in.
Gain: defines the maximum broadband gain in dB that is applied
Bass Boost: defines the maximum gain in dB that is additionally applied to the low frequencies (< 500Hz)