Sound Cue Reference

In Unreal Engine, a Sound Cue is an audio asset that encapsulates complex sound design tasks within a node graph. Sound Cues provide audio designers freedom to dynamically change parts of a sound effect's design by arranging and modifying Sound Nodes to create complex and interesting audio output.

In the Sound Cue Editor, a list of Sound Node types is provided within the Palette panel. Selecting a node in the Viewport panel will display the node's properties in the Details panel.

For more about working with Sound Cues, see the Sound Cue Editor and Sound Cue Editor UI documentation.

Named Parameters

In some Sound Nodes, you can declare a parameter by entering a new parameter name. When you enter a parameter name in a node, it will create a parameter with that name.

You can name the parameter whatever you want. However, when you use an Audio Component Function to set the parameter's value, its In Name field must exactly match the Parameter Name you gave it.

You cannot set the values for a named parameter from within a Sound Cue. A recommended workflow would be:

• Add a Sound Node.
• Enter a name in the node Parameter Name field.
• Call the relevant audio component function from within a Blueprint, or in code, using the appropriate Set [Name] Parameter function.
• Add the same name to the In Name parameter. This will get the Sound Cue to respond as expected.

The table below shows the nodes that can use named parameters, and the corresponding parameter setting functions.

Output Node

An Output node is required in every Sound Cue and works as an end point for the audio signal path in the node graph. The Output node's properties are relative and affect all of the audio output contained within the Sound Cue.

Attenuation Node

The Attenuation node controls volume for a sound based on the distance of the sound source from the listener.

The Attenuation Settings can be set to an existing Sound Attenuation asset or manually specified in the node's properties by enabling the Override Attenuation setting.

For an overview on attenuation and how it works, see the Sound Attenuation documentation.

Stereo files play evenly on the left and right channels, and attenuate to allow volume fades between the Radius Min and Radius Max values, but they are not spatialized.

Sound Cues that do not contain an Attenuation node are not localized, and play consistently at the Sound Cue volume setting.

Branch Node

The Branch node selects an input node based on the value of a named Boolean parameter of True, False or Parameter Unset.

Parameter Unset is the output that plays when the value of a named parameter has not been set. For example, if the parameter is saved as Name in the Branch node, but the user hasn't called SetBooleanParam(Name, [true or false]), the Sound Cue will use the Parameter Unset input pin, not the True or False pin.

For more information about named parameters, see the Named Parameters section of this page.

Concatenator Node

The Concatenator node is used to play sounds sequentially (for example, creating a simple BGM playlist that plays through a series of specified tracks). While this node handles sequential playback, it will also add a small delay between each asset.

Initially, this node has two input pins. You may add more pins by clicking the Add input button on the node or remove pins by right-clicking them and selecting "Delete Input" from the context menu.

Continuous Modulator Node

The Continuous Modulator node provides a way to control named parameters for volume and pitch modulation in real time. A typical example would be using the velocity of a vehicle to correspond to the pitch of an engine sound. This modulator needs to be hooked up in code or Blueprint to work, and does not function on its own within the Sound Cue Editor. However, you can change pitch and volume from within the Sound Cue Editor.

By setting maximum and minimum values, you can determine the range of randomization.

The pitch and volume of the input sound will default to a uniform distribution, but you can change them in the Sound Cue Editor to any other type.

For more information about named parameters, see the Named Parameters section of this page.

Crossfade by Distance Node

The Crossfade by Distance node provides the ability to fade between two or more input sounds based on the distance from the Sound Cue's origin to the listener.

For example, a gunshot heard at a distance will sound different from a gunshot up close. This node can calculate the distance the listener is from the shot and play the sound based on a short or long distance, or a mix of the two.

This node differs from the Attenuation node in that the sound will only play if it is within the minimum and maximum distance settings.

Sound Nodes can be connected directly to the Crossfade by Distance node inputs, but you can also add nodes between them for independent control per layer.

Initially, this node has two input pins. Add more pins by clicking Add input.

If you want to hear the sound up close, then setting Fade in Distance Start to 0 might be a good option.

These values can be set independently for each attached sound.

Crossfade by Param Node

The Crossfade by Param node works similarly to the Crossfade by Distance node, except that the Crossfade by Param node provides a way for you to manipulate the value of a named parameter that controls the crossfade programmatically (with code or Blueprints).

Initially, this node has two input pins. You may add more pins by clicking the Add input button on the node or remove pins by right-clicking them and selecting "Delete Input" from the context menu.

For more information about named parameters, see the Named Parameters section of this page.

If you want to hear the sound up close, then setting Fade in Param Value Start to 0 might be a good option.

The Crossfade by Param node does not support negative values.

Crossfade by Param Example

Click image for full size.

The diagram above shows the expected volume change over time of two parameters based on the the given property values.

Delay Node

The Delay node inserts a delay into the Sound Node chain to cause a pause before the input sound is passed to the output. The amount of the delay is a random value between the Delay Min and Delay Max values specified in the Details panel.

Dialogue Player Node

The Dialogue Player node is a way to set up a Dialogue Wave asset to be played under specific conditions.

Since Dialogue Waves are expected to be used purely for spoken dialogue, the Dialogue Player node requires that you specify both the speaker and the targets of the dialogue being played. This allows the Dialogue Wave to play the correct audio Asset depending on the specific context, such as plurality, gendered language, or for localization purposes.

Doppler Node

The Doppler node simulates a Doppler effect, in which a sound's pitch changes based on the source's movement in relation to the listener. The pitch will increase as the source approaches the listener and will decrease as the source moves away.

A common real world example of this is the sound of a passing ambulance's siren.

Enveloper Node

The Enveloper node creates an envelope where a sound's volume and pitch are manipulated over a specified time period via distribution curves. These curves can be edited using the embedded Curve Editors, or can be based on curves defined in an existing Float Curve Asset already in the Content Browser.

Optionally, the envelope can be set to loop a set number of times or even indefinitely.

You can use the properties in the Modulation category to randomize predefined values across set points on the envelope.

Group Control Node

The Group Control node controls which sounds are played based on the number of active sounds, while giving priority to the first available group.

Initially, this node has two input pins. You may add more pins by clicking the Add input button on the node or remove pins by right-clicking them and selecting "Delete Input" from the context menu.

Looping Node

The Looping node is used to loop sound indefinitely or a set number of times.

You can loop multiple audio files independently when used in conjunction with the Mixer node.

A Looping node should only be used for logical or procedural looping such as introducing a delay because these sounds will not play seamlessly. If you want a sound to loop seamlessly and indefinitely, use the Looping flag on the Wave Player node (see below) for the sound.

Mature Node

With the Mature node, you can flag input nodes as intended for mature audiences. This node uses the value of UEngine:bAllowMatureLanguage to determine whether input nodes should be played.

Initially, this node has two input pins. You may add more pins by clicking the Add input button on the node or remove pins by right-clicking them and selecting "Delete Input" from the context menu.

Mixer Node

The Mixer node defines how concurrent sounds in a Sound Cue are mixed together by providing volume control for each individual input.

Initially, this node has two input pins. Add more pins by clicking Add input.

Modulator Node

The Modulator node is used to randomize volume and pitch modulation. You can set maximum and minimum values to determine the range of randomization. When the Sound Cue is triggered, it randomly selects a value within that range.

To set a consistent level for volume or pitch, set the same values for both the minimum and maximum values. This node can also be used to adjust relative volumes of multiple Sound Wave nodes contained within a Sound Cue.

If the Modulator node is used in combination with the Looping node, it will randomize on the each Sound Cue trigger and not on each individual loop.

Oscillator Node

The Oscillator node is used to introduce continuous pitch and volume oscillation. This is useful when looping sounds to create a greater degree of ongoing movement.

By setting maximum and minimum values, you can determine the range of randomization.

Quality Level Node

By default, there are no quality levels; the designer must add them to the Project Settings for the node inputs to populate. Once populated, node branching can be used to switch between various levels of SoundCue graph complexity. This provides a way for designers to use simpler SoundCue graphs for lower-powered platforms.

The Quality Level node uses GameUserSettings AudioQualityLevel (or the editor override) to choose which branch to play.

At runtime, this node will only load into memory the Sound Waves connected to the branch that is selected.

Random Node

The Random node is used to randomly trigger a node from the list of connected input nodes. Weight values control the probability of a node being triggered relative to the other nodes connected to the Random node.

When an input node is selected randomly, the Sound Cue will play the entire data flow of that selected input.

Initially, this node has two input pins. You may add more pins by clicking the Add input button on the node or remove pins by right-clicking them and selecting "Delete Input" from the context menu.

SoundClass Node

The SoundClass node provides a way to remap which Sound Class asset used with the input node.

For more information about named parameters, see the Named Parameters section of this page.

Switch Node

The Switch node selects an input node based on the value of a runtime integer parameter. The specified parameter must be declared in either code or Blueprints.

Initially, this node has four input pins. You may add more pins by clicking the Add input button on the node or remove pins by right-clicking them and selecting "Delete Input" from the context menu.

For more information about named parameters, see the Named Parameters section of this page.

Wave Param Node

The Wave Param node uses a named parameter to determine whether to play a different Sound Wave than the one feeding into the input pin. If the specified parameter is set to the name of a valid Sound Wave asset, that asset is played.

If an optional input node is connected and the named parameter is valid, the Wave Param will override the input node when the Sound Cue is played.

For more information about named parameters, see the Named Parameters section of this page.

A potential use for this node would be to play dynamic dialogue lines in between static blip sounds in order to simulate dialogue over a radio. In this way, the same Sound Cue can be reused to great effect.

Wave Player Node

The Wave Player node contains a reference to a Sound Wave asset to be played with the Sound Cue.

Add Comment

Comments can be added anywhere on the Sound Cue. They do not affect the output, but instead are used to call attention to or explain details in the node arrangements or uses.

The comment appears at the top of the frame. There is no limit to the length of the comment.

The comment frame's size can be changed by dragging the lines in the lower right corner and the position can be changed by dragging from anywhere else on the frame. Wherever positioned, it will appear behind the nodes.

If you move a comment box, it will bring any fully contained Sound Nodes along with it.

You can also add a comment by selecting multiple nodes, right-clicking a selected node, and then selecting Create Comment from Selection from the context menu.

Examples

Below are examples of more complex Sound Cue arrangements. You can click on each image to expand it.

This Sound Cue plays one sound if a parameter is set to true, and another if it is set to false.

This Sound Cue changes the Sound Classes of the Sound Waves.

This Sound Cue mixes together Sound Waves with a variety of properties, including attenuation, randomization, looping, and delays.