Wikis / Unreal Wiki / Legacy:Triggering Sounds

In UT, there are several methods used to have sounds in a map that can be triggered. (Nobody has taken the time to write about it for UT2003 yet!)

For one-shot sounds, the best method is probably the SpecialEvent actor, although it doesn't allow volume control. For looping sounds, things are a little more complicated: the problem is making the sound stop.

The methods are:

DynamicAmbientSound

DynamicAmbientSound (description needed)

TriggeredAmbientSound

TriggeredAmbientSound works, but only if bStatic under Actor (UT)/Advanced is manually set to False. There's also YoMammy's custom script on that page, which fixes all of the problems with TAS.

TriggerLight

TriggerLight can be set so a sound is heard when activated, but no light is produced. This works fine with looping sounds.

Set the following properties:

• Lighting -> LightBrightness to a non-zero number. This will set the maximum volume for the sound
• Lighting -> LightType to LT_Steady
• Lighting -> LightRadius to 0 – this is so the light doesn't show
• Object -> InitialState – Choose a triggering type. See the TriggerLight class page for the list & details

Advantages:

• can be set to stop. This means a looping sound can be used.
• the sound can be made to fade up or down gradually in the same way that TriggerLight can make the light fade.
• the maximum volume can be set with LightBrightness

To make a looping sound play for a set time and then stop, set the TriggerLight's Object.Initial state to "TriggerToggles", and trigger a Dispatcher which in turn triggers the TriggerLight twice – see Trigger Systems for a full explanation of this technique.

SpecialEvent

A SpecialEvent actor can be used to play a sound. Drawbacks to this method:

• only one-shot sounds work with this; looping sounds will play continually until the player moves out of range of the SpecialEvent.
• the volume can't be specified directly; the sound will play at maximum volume unless you set the TransientSoundVolume property of the SpecialEvent to a value between 0.000 and 1.000. See Actor (UT)/Sound for more info.
• If you forget to set the Object -> InitialState property it will take you bloody ages to work out what you've missed.

Hidden Mover

This is a dirty trick and best seen in DM-Pressure: the hissing sound made by the pressure chamber is make by two simple cube movers that move in solid space nearby. Their mover sounds provide the noises.

• Advantage: you get not just one sound, but with OpeningSound and OpenedSound you can set start and end sounds. See Mover for more on this.
• Drawback: you can't set the volume of these extra sounds; they're played at maximum.
• Drawback: it's messy

Related Topics

• Dynamics topic page: triggers & sounds
• Types of Trigger: summary of trigger types