FMOD Studio

The audio files that we'll be using to create a looping audio effect for the campfire, are stored in the _Audio_Assets/FMod Studio/chapter_03/ folder of your Audio Showcase assets' installation directory as l_global_particle_fire_01.wav, l_global_particle_fire_02.wav, l_global_particle_fire_03.wav, l_global_particle_fire_04.wav and l_global_particle_fire_05.wav.

Create a new folder in the Audio Bin and Event tab of your FMOD project called Particle, and drag/drop the five audio files into them to create a new 3D multi-instrument Event. Name it l_global_particle_fire. 

Select the l_global_particle_fire Event and click on the Multi-instrument timeline at the center of the screen; you should see the following playlist of audio assets that make up the Event in the bottom panel.

Playlist

Click the  button to have the audio files play in a loop when the Event is triggered. To make sure the Event loops properly, activate the Async option; this ensures that the audio assets play in their entirety once triggered, especially if they aren't of the same length. You'll notice the waveforms of all five audio assets are stretched to fit the time scale on the multi-instrument; this is just a visual change as the assets sound exactly the same as before.

We then need to create a Loop Region to specify the area of the Multi-instrument that needs to be looped. Since we'd like for the entire Multi-Instrument's timeline to loop:

• Right-click the Multi-instrument timeline and select the New Loop Region option from the context menu.
• This creates a new blue marker above the Multi-instrument timeline. Play the Event and listen to the result.

Finally, add this l_global_particle_fire Event to a new Bank called Particle, before rebuilding all SoundBanks by pressing the F7 key. Switch back to the ACE and create a new Library called Particle in the Audio System Controls panel.

• Drag and drop the l_global_particle_fire Event we just created into the Particle Library to create an audio trigger of the same name.
• Also add the Particle Soundbank from the Middleware Data panel to the Preloads library before reloading the audio engine. 

Wwise

The audio files that we'll be using to create a looping audio effect for the campfire are stored in the _Audio_Assets/Wwise/chapter_03/ folder of your Audio Showcase assets' installation directory as l_global_particle_fire_01.wav, l_global_particle_fire_02.wav, l_global_particle_fire_03.wav, l_global_particle_fire_04.wav and l_global_particle_fire_05.wav.

Begin by creating a new Actor-Mixer called Particle in the Default Work Unit of the Actor-Mixer Hierarchy, a new Particle folder in the Events tab, and a new Particle SoundBank in Wwise. Then drag and drop all assets from the _Audio_Assets/Wwise/chapter_03/ folder into a new Random Container within the Particle Actor-Mixer, and name the Container l_global_particle_fire.

The goal is to create a looping fire particle that plays random audio files on each loop for maximum variety. To do this, a parent Random Container needs to created for our current l_global_particle_fire Container:

• Right-click the l_global_particle_fire Random Container and select the New Parent → Random Container option. Name the parent Random container l_global_particle_fire.
• Select the parent l_global_particle_fire Container and then in the General Settings tab of the Property Editor, set the Play Mode to Continuous. Select the Loop option, activate Transitions, and set the transition Type to Xfade(power) from the dropdown.

Transitions

• Next, create a new Event for the parent l_global_particle_fire Container by right-clicking it and selecting the New Event → Play option.
• In the Events tab, create a new folder called Particle, and move the Play_l_global_particle_fire Event you just created into it. 
• Finally, add the Particle Event folder to the Particle SoundBank. Save the project and Generate All Soundbanks.

Switch back to the ACE and create a new Library called Particle in the Audio System Controls panel.

• Drag and drop the Play_l_global_particle_fire Event we've just created into the Particle Library to create an audio trigger of the same name.
• Also, add the Particle Soundbank from the Middleware Data panel to the g_preloads library before reloading the audio engine. 

SDL Mixer

Audio for the campfire has been included as Play_l_global_particle_fire.ogg, under the _Audio_Assets/SDL_Mixer/chapter_03/ folder of the Audio Showcase Level assets' installation directory.

• Create a new Library called Particle under the /Assets/Audio/sdlmixer/assets directory of your project, and copy the file into it.
• Set the value of the Max Distance property to 10 in the Properties panel.
• Also activate the Infinite Loop property.

Save the created Library and reload the audio engine before proceeding to link the Trigger to the fire particle.

As the name implies, the Stop on Death property causes an audio trigger to stop playing when the particle is disabled. The Follow Particle property meanwhile, causes the sound of an audio trigger to follow the particle as it is moved around a scene; it is hence recommended that this setting be used when the audio trigger is designed to loop.

FMOD

If using an FMOD middleware implementation, you'll have noticed that the sound of the campfire trigger reduces as the player moves farther away. This is because FMOD Studio sets a default attenuation for each 3D Event.

To view the Play_l_global_particle_fire Event's attenuation settings within your FMOD project:

• Select the Play_l_global_particle_fire Event from the Events tab of your FMOD project.
• Click the Event's Master Track  to see the Spatializer Effect panel at the bottom of the window; this is a standard effect applied by FMOD Studio to all 3D Events.

Within the Spatializer Effect panel is a red curve that describes how the volume of the Event changes with distance; specific Min and Max values can be set from below the curve. 

Any changes made to the Min and Max values of Play_l_global_particle_fire's attenuation can be tested within FMOD's Sandbox as follows.

• Select Window → Sandbox from FMOD Studio's main menu. This opens a window with a small arrow at the center of a grid, as shown in the image below, representing the listener's position and orientation.
• Drag and drop the Play_l_global_particle_fire Event from the panel on the left onto the grid. This creates a new circle on the grid that represents the position of the Event sound with respect to the listener; click the Event circle and move it using the LMB to change its distance from the listener.
• With the position of the Event and its distance from the Listener set, the effect of different Attenuation curves and Min/Max values can be heard by double-clicking the Event circle to trigger it.

FMOD Sandbox

In the real world, there is not just a reduction in volume but also a loss of high frequencies as distance increases. To implement this frequency modulation in a game environment, we need to create a parameter that changes over distance.

Open the Preset Browser using the Window → Preset Browser option from your FMOD Studio project window. 

• Right-click within the light-grey pane of the Preset Browser and select the New Parameter option from the menu. 
• Since we need to use a Built-In Parameter, select the Built-in: Distance option in the Add Parameter window that opens; its Range can be set from 0 to 100, meaning that when the Event is 105 meters away from the listener, the value of the Distance parameter will be 100, its highest value.
• Click OK on the Add Parameter window to create the Parameter and close the Preset Browser. 

We now need this Distance parameter to drive the cut-off frequency of a Low Pass filter.

• First, go back to the Play_l_global_particle_fire Event in the Event Editor tab of your FMOD project, select its Master Track, and add a new Effect to it by clicking next to its SpatializerEffect panel in the bar down below. Select the Add Effect →Multiband-EQ option from the menu.
  

  Info
  A multiband-EQ is used to reduce high frequencies over distance using a low-pass filter.

  
  

• Right-click the yellow Freq. (A) value on the Multiband EQ panel and select Add Automation; this adds a new track called Multiband EQ below the Master track.
• Now, above the Audio 1 track of the Event is a tab called Timeline. Click the + icon beside it, and select the Distance parameter from the Select Parameter window that appears, as shown.

Select Parameter

You should now see the scale above the Audio 1 track change to the range of 0 - 100, which corresponds to the range of the Distance Parameter we created. By adding different points to the curve of the Multiband EQ track, you may now change the cut-off frequency of the low-pass filter at different values of the Distance Parameter as shown in the GIF above.

Test various cut-off frequency values in combination with different attenuation settings using the FMOD Studio Sandbox and, when satisfied, rebuild all Soundbanks, reload the audio engine in the ACE, and jump into Game Mode to hear your changes.

Wwise

You'll notice that the sound of the campfire remains constant regardless of the player's position, because it isn't 3D spatialized. To change this:

• Select the Particle Actor-Mixer on Wwise and open the Positioning tab in the Property Editor.
• Tick the Override Parent box and set the 3D Spatialization field to Position + Orientation; this positions the sound in 3D space relative to the listener's orientation.

We now need to add attenuation to the sound, which defines how the sound changes over distance; Wwise gives us the option to not only change the volume of the sound, but also set low/high-pass filters and change the spread of the sound.

Aspects such as the frequency and spread of a sound are stored within an Attenuation Share Set, which can also be used by multiple other sounds. 

• Click on the icon within the Attenuation section in the Properties tab of the Property Editor. 
• Select the New option from the menu to create a new Share Set, and name it Attenuation_30m. As this Share Set is now assigned to the Particle Actor-Mixer, clicking the Edit button opens the Attenuation Editor as shown.

Attenuation

The red line that you see on the Attenuation Settings graph represents the volume of the sound, which is active by default. Try setting the Max distance to 30.

Under the Curves section is a list of other parameters that can be activated; since we'd like to add a low pass filter for attenuation, change the value of the Low-pass filter to Custom in the Curves section; you should now see a blue line in the Attenuation Settings grid.

• Double-click on a curve to add a new point on it.
• Right-click to apply a specific smoothing. It must be noted that curves are usually worse for performance than linear lines, because of the increased number of calculations that have to be made.

Feel free to use the GIF above for reference.

Test various attenuation settings and, when satisfied, generate all SoundBanks, reload the audio engine in the ACE, and jump into Game Mode to hear your changes.