Introduction to Procedural Audio with SoundSeed

Interactive media demands audio that adapts on the fly. Pre-recorded sound effects, while reliable, quickly become repetitive and can break immersion when a player’s actions don’t match a static file. Wwise’s SoundSeed technology solves this by generating sounds in real time, responding to game parameters such as speed, altitude, weather, or user input. This guide walks you through the core concepts, setup, configuration, and integration of SoundSeed, equipping you with the knowledge to build dynamic, responsive soundscapes for any project. Whether you are designing a roaring engine, a shifting wind, or a crackling fire, SoundSeed offers a powerful, flexible foundation.

Understanding SoundSeed Technology

SoundSeed is a procedural audio engine built into Wwise (the Audiokinetic audio middleware) that creates sounds algorithmically rather than relying solely on static recordings. It uses a set of mathematical models and synthesis techniques to produce audio that evolves continuously. Unlike sample-based systems that crossfade between clips, SoundSeed generates every sample from parameters you define, resulting in infinite variation without the memory cost of multiple recordings.

The technology excels in scenarios where sounds have natural variability – wind that gusts differently each time, a vehicle engine that changes with throttle and load, or water that reacts to the shape of a shoreline. SoundSeed achieves this through a combination of additive synthesis, subtractive synthesis, and granular processing, all controllable through exposed parameters.

Key differences from traditional sound effects:

  • Dynamic vs. static: A traditional wind sound is a loop; SoundSeed wind changes texture based on intensity, direction, and turbulence.
  • Memory efficiency: A SoundSeed object uses a tiny footprint (often a few kilobytes) compared to a high-quality PCM loop that could be megabytes.
  • Responsiveness: Parameters can be updated every frame (or per game event), enabling seamless transitions – for instance, an engine that smoothly moves from idle to full rev without crossfade artifacts.

SoundSeed is not a magic bullet; it works best for continuous, evolving sounds and less well for discrete one-shot effects such as a single gunshot or footstep (though those can be combined with SoundSeed layers). Understanding this scope helps you decide where to invest your procedural audio efforts.

Setting Up SoundSeed in Wwise

Before diving into sound design, ensure you have a working Wwise project (version 2021.1 or later recommended) and the SoundSeed plugins installed. The SoundSeed plugins come with Wwise by default – you do not need additional purchases, but some advanced SoundSeed sources (e.g., SoundSeed Wind, SoundSeed Engine) are included in the standard installer. Verify by opening Wwise and checking the Project Explorer under the “Sound Seeds” category.

Step 1: Create a SoundSeed Object

  1. Open your Wwise project and navigate to the Audio tab.
  2. Right-click the Interactive Music Hierarchy or SoundBank folder where you want to place the sound.
  3. Select New Child > SoundSeed (you will see options like SoundSeed Wind, SoundSeed Engine, SoundSeed Water, or a generic “SoundSeed Generator”).
  4. Name your object descriptively, e.g., “Wind_Storm_Layer”.

Step 2: Configure the Source Plugin

In the Property Editor for the new object, click the Source tab. Here you select which SoundSeed generator to use:

  • SoundSeed Wind: For outdoor wind, gusts, and atmospheric noise. Built on filtered noise with separate controls for turbulence and speed.
  • SoundSeed Engine: For vehicle and machinery sounds. Uses multiple oscillators and filter models to simulate combustion and mechanical motion.
  • SoundSeed Water: For flowing water, waves, and splashes. Based on resonant filters and noise shaping.
  • SoundSeed Generator (Generic): A flexible synthesis engine with oscillators, noise, filters, and an envelope. Suitable for custom procedural effects like fire, rain, or electrical hum.

Select the appropriate generator and apply it. You will now see its specific parameters in the same Source tab.

Step 3: Set Basic Parameters

Each SoundSeed source exposes a set of parameters that define the initial behavior. For example, the SoundSeed Wind source includes:

  • Intensity: Controls overall energy (0 to 100). Higher values produce louder, more turbulent wind.
  • Speed: Affects the rate of change in the wind texture. Fast speed gives gusty effects; slow speed yields a steady background wind.
  • Pitch Offset: Shifts the overall frequency content.
  • Randomness: Adds stochastic variation to prevent periodicity.

Set these to a starting point you can hear in the Wwise Transport Control panel. Play the sound and adjust until you have a rough base layer.

Core Parameters and Their Impact

Mastering the parameters is critical to creating natural-sounding, responsive audio. While each SoundSeed source has unique parameters, several concepts apply universally.

Intensity and Energy

Most SoundSeed sources have a master Intensity parameter. This does not just change volume; it modifies the spectral shape. In the wind source, higher intensity adds more high-frequency energy and turbulence. In the engine source, intensity correlates with engine load and RPM. Use Intensity as the primary mapping for game state – for instance, character speed, engine throttle, or storm severity.

Modulation and Rate

Modulation parameters control how quickly the sound evolves. For wind, “Speed” (or “Turbulence Rate”) determines how fast the gusts change. For water, “Agitation” controls the frequency of wave peaks. In general, higher modulation values create a more chaotic, active sound – ideal for combat or high-speed scenes – while low values produce a calm, ambient texture.

Randomness and Variation

Without randomness, procedural sounds can become cyclical and sterile. SoundSeed includes a “Randomness” or “Stochastic” parameter that adds controlled noise to the internal processes. A value of 0 yields a deterministic output (same parameters = same sound each time). Moderate randomness (20–40%) creates natural variation without losing character. High randomness can produce unpredictable, organic textures, but may become too chaotic for some applications.

Filter Characteristics (Tone Control)

Many SoundSeed sources have built-in filters (low-pass, high-pass, band-pass) or “brightness” controls. Use these to change the timbre based on context. For example, an underwater filter can be applied to all SoundSeed sounds when the player submerges. Alternatively, you can automate a low-pass filter to simulate occlusion from walls or distance.

Advanced Configurations: Layering and Blending

Complex soundscapes often require more than a single SoundSeed object. Layering multiple instances is a powerful technique to achieve rich, detailed audio.

Creating Layered Soundseed Objects

Suppose you want a wind sound that has both a low, rumbling component (for the sense of power) and a high, whistling component (for detail). You could create two SoundSeed Wind objects:

  • Wind_Rumble: Set parameter Intensity to high, Speed low, and apply a low-pass filter at 300 Hz.
  • Wind_Whistle: Set Intensity moderate, Speed high, and a high-pass filter at 2 kHz.

Place both objects in a Wwise Container (e.g., a Random or Sequence Container) so they play simultaneously. This layered approach allows you to mix independent parameters in real time – you can keep the rumble steady while making the whistle more active during gusts.

Using RTPCs to Drive Parameters

Real-Time Parameter Controls (RTPCs) are the bridge between your game and SoundSeed. For each parameter you want to control dynamically, add an RTPC curve in the Wwise property editor:

  1. In the Property Editor of the SoundSeed object, click the RTPC tab.
  2. Select a parameter (e.g., Intensity) and click Add Game Parameter.
  3. Choose a game parameter from your defined list (e.g., “Player_Speed” or “Wind_Strength”).
  4. Define the curve – for example, map Player_Speed 0 to 100 to Intensity 20 to 80.

Now when your game sets the Player_Speed value via the Wwise SDK, the SoundSeed object automatically adjusts. You can also attach RTPCs to multiple parameters per object, creating intricate interdependencies. For instance, you might have Player_Speed control not only Intensity but also Pitch Offset and Filter Cutoff, giving a cohesive response.

Blending Between Different Soundseed Types

For a lava flow or a fiery explosion, you might combine a SoundSeed Fire (created from the Generic generator) with a SoundSeed Crackle (using Granular synthesis). Use the Wwise Blend Container to crossfade based on a game parameter like “Temperature”. This approach prevents a hard cut between states and maintains continuous evolution.

Integration into Game Engines

Setting up SoundSeed inside Wwise is only half the work; you must also integrate it into your game engine (Unity, Unreal, Godot, or custom C++). The following workflow covers the essential steps.

Exporting SoundBanks

Once you have finalized your SoundSeed objects and their RTPC mappings, generate SoundBanks as usual:

  1. In Wwise, click Project > SoundBank Settings and ensure the correct platforms are selected.
  2. Generate the SoundBanks (Project > Generate All SoundBanks or Ctrl+Shift+G).
  3. Note that SoundSeed objects are very lightweight – the entire SoundBank may be only a few KB, which speeds up loading and reduces memory pressure.

Triggering and Parameter Updates from Code

In your game engine, use the Wwise SDK to post events and set game parameters. For example, in Unity with the Wwise integration:

// Post a SoundSeed-based event
uint eventID = AkSoundEngine.GetIDFromString("Play_Wind_Storm");
AkSoundEngine.PostEvent(eventID, gameObject);

// Update a game parameter that drives SoundSeed RTPCs
float windStrength = Mathf.Clamp01(GetWindFromWeatherSystem());
AkSoundEngine.SetRTPCValue("Wind_Strength", windStrength * 100f, gameObject);

Similarly, in Unreal Engine using the Wwise UMG integration:

// Post event
FAkAudioDevice* AkAudio = FAkAudioDevice::Get();
if (AkAudio)
{
    AkAudio->PostEvent("Play_Wind_Storm", GetOwner());
}

// Set RTPC value
AkAudio->SetRTPCValue("Wind_Strength", CurrentWindSpeed);

Update the RTPC values each frame (or at a lower frequency for smooth interpolation) to ensure the sounds react without latency. The Wwise sound engine interpolates RTPC changes over time based on the curve settings you defined in Wwise, so you do not need to worry about stepping artifacts.

Testing in Real Time

During development, use the Wwise Profiler to monitor SoundSeed parameter behavior. Connect the profiler to your running game and inspect the actual parameter values your code sends, as well as the output of the SoundSeed generator. This helps you catch issues like incorrect scaling or unexpected parameter ranges.

You can also use the Wwise Authoring tool’s Game Sync Monitor to manually change RTPC values and hear the effect immediately, without recompiling your game. This iterative workflow speeds up sound design significantly.

Practical Workflow Tips

Over the years, sound designers have developed best practices for procedural audio with SoundSeed. Here are key tips to maximize quality and efficiency:

Start Simple and Layer Up

Resist the temptation to load a single SoundSeed object with dozens of parameters. Begin with two or three parameters (Intensity, Speed, and Pitch offset) and listen. Add complexity only when the base sound lacks the desired character. Layering multiple simple SoundSeed objects is often more natural than overloading one.

Use Envelopes for Transitions

Some SoundSeed parameters can be automated with Wwise’s built-in Envelope (ADSR). For instance, when a player enters a cave, you can fade the wind speed parameter over 2 seconds. This can be achieved by setting an RTPC with a gradual curve, but an envelope can also be attached directly to the SoundSeed object’s properties. Envelopes are useful for event-driven changes like an explosion’s aftermath or a vehicle starting up.

Combine with Traditional Samples for Punch

Procedural sounds can sometimes lack the “character” of recorded samples, especially for transient-heavy effects. A common hybrid approach is to layer a SoundSeed engine with a short recording of a real engine rev for a starting burst. Use Wwise’s Multi-Source container to blend them. The sample provides the initial impact, while SoundSeed sustains the engine sound with infinite variation.

Monitor Performance

Although SoundSeed is efficient, running many high-complexity instances can strain CPU. Each SoundSeed source uses some CPU for synthesis. Use the Wwise CPU Profiler to measure the cost. If you exceed your target, consider lowering the sample rate of some low-priority sounds, reducing the number of voices, or using a less complex generator (e.g., a filtered noise source instead of full additive synthesis).

Iterate with Context

SoundSeed sounds never sound exactly right in isolation. Always test them inside your game environment with visuals and other audio layers. A wind sound that sounds good in a quiet Wwise editor might disappear behind music or sound too loud in a forest scene. Use Wwise’s Game Object Viewer to hear the sound as it would play in the scene, with all other audio active.

External Resources and Documentation

To deepen your understanding of SoundSeed, explore these official and community resources:

Conclusion

Wwise’s SoundSeed technology is a versatile tool for generating dynamic sound effects that elevate interactive experiences. By understanding its procedural nature, mastering parameter configuration, and layering multiple sources, you can craft audio that feels alive and responsive. Integration through RTPCs and the Wwise SDK links your game logic directly to the sound engine, allowing real-time adaptation without the memory overhead of static clips. Experiment with different generator models, combine them with traditional samples, and always test within the context of your game. The result is an audio environment that players will notice for its seamless reactivity and natural variation – a hallmark of professional sound design in modern interactive media.