Sound Cue Reference

In Unreal Engine (UE4), a Sound Cue is an audio object that encapsulates complex sound design tasks in 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, creating complex and interesting audio output.

The sound nodes appear in the Palette panel when the Sound Cue Editor is open. When you add a node to the Sound Cue and select it, the properties for that node display in the Details panel.

For more about Sound Cues, see Sound Cue Editor and Sound Cue Editor UI.

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.

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You can name the parameter whatever you want. However, when you use an audio component function to set that param, 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 Cue 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 Set [Name] Parameter function.
• Add the same name to the In Name category. This will get the Sound Cue to respond as expected.

The table below shows the nodes that can use parameters, and the corresponding audio components.

For more on how audio components interact with other Assets, see Audio Components.

Attenuation Node Properties

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

To use the Attenuation node to override your Sound Cue’s attenuation settings, enable the Attenuation node’s Override Attenuation checkbox in the Sound Cue Editor.

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

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 Properties

The Branch node selects a child node based on the value of a 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.

Concatenator Node Properties

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.

The node initially has two input pins. Add more by clicking Add input.

Continuous Modulator Node Properties

The Continuous Modulator node provides a way to control gameplay 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 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.

Crossfade by Distance Node Properties

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.

By default, the node initially has two input pins. Add more pins by clicking Add input.

The top input in the node is 0 in the Details panel.

These values can be set independently for each attached sound.

Crossfade by Param Node Properties

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 the parameter that controls the crossfade programmatically (with code or Blueprints).

You can save the parameter settings by naming them.

Delay Node Properties

The Delay node inserts a delay into the audio 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 Properties

The Dialogue Player node is a way to set up a Dialogue Wave sound 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 according to the speaker's voice, along with any gender/plural/honorific handling that needs to occur for localization purposes.

Doppler Node Properties

The Doppler node simulates a Doppler effect, in which sounds increase in pitch as the distance lessens, then decrease as it lengthens. A real world example is the sound of a siren as it approaches then drives past.

Enveloper Node Properties

The Enveloper node is a way to create an envelope with optional looping ability that can control the volume and pitch of a sound over time 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.

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

The Details panel of the Enveloper node contains various options for creating envelope curves:

• Volume Curve: The distribution that defines the volume envelope.
• Pitch Curve: The distribution that defines the pitch envelope.
• Create External Curve button: Create your own curve manually, then save it as a Float Curve Asset to be reused elsewhere. This option is available for both volume and pitch curves. For more on using curves, see Curve Editor.

Group Control Node Properties

The Group Control node determines which Sound Wave to play based on what sounds in the defined groups are already playing, and their proximity to the listener.

When a new sound plays, the first group with an available slot will be chosen.

Looping Node Properties

The Looping node is used to loop a Sound Wave.

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 Properties

With the Mature node, you can label a specific node or Sound Cue for content that would be labeled Mature by the ESRB (Entertainment Software Rating Board) rating system. When you use this node on a Sound Wave in a Sound Cue, it will filter out the M-rated content in any versions of your game that have restrictions programmed in.

Mixer Node Properties

The Mixer node defines how concurrent sounds in a Sound Cue are mixed together. This is not a downmix—there is no reduction in the number of individual Sound Waves in the Sound Cue. The volume for each input can be set independently.

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

Modulator Node Properties

The Modulator node is used to add random 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 Min and Max values the same.

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 conjunction with the Looping node, it will randomly select based on Sound Cue retrigger, not per-loop revolution.

Oscillator Node Properties

The Oscillator node is used to add continuous pitch and volume oscillation over time. 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 Properties

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 Properties

The Random node is used to randomly trigger a Sound Wave node from within a group of possible Sound Wave nodes. Weight values control the probability of a Sound Wave node being triggered relative to the other nodes connected to the Random node.

Each trigger is its own data flow. This means that if the Random Output pin is connected to more than one node (such as an Oscillator node and a Delay node), then each of these will play independently.

When enabled, the checkbox RandomWithoutReplacement will exhaust the entire list of possible sound nodes before repeating a sound.

Sound Wave nodes can be connected directly to a Random node, but you can also add other nodes between the Sound Waves and this node for additional control.

By default, the node initially has two input pins. Add more pins by clicking Add input.

SoundClass Node Properties

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

Switch Node Properties

The Switch node selects an input node based on the value of an integer parameter.

Wave Param Node Properties

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

A simple example would be using this node for dialogue. You could have a radio sound where, on the beginning of the Sound Cue playback, you hear a little static blip, the dialogue plays, then you hear the static blip again on the end. In this way, you could dynamically feed in different dialogue lines while using the same Sound Cue.

You can set the parameter in code or in Blueprint.

Wave Player Node Properties

The Wave Player node contains a reference to the raw .wav file to be played.

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 in the top bar. There is no limit to the length of the comment, but they should be as brief as possible.

The comment frame can be adjusted. Wherever positioned in the Sound Cue, it will appear behind the nodes.

Examples

Below are examples of more complex Sound Cue arrangements.

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.