This is not exposed in the API directly. However, there are some techniques for that:
Method 1 (require coding)
Create your own Effect plug-in. You will receive the raw PCM data. You could, for example, use an FFT to extract the spectrum, and send it to your game directly.
You can take a look at the following help section in the Wwise SDK Documentation:
https://www.audiokinetic.com/library/edge/?source=SDK&id=goingfurther__newplugins.html
You will be able to look at the Delay plug-in as an example.
SDK\samples\Plugins\AkDelay
Method 2 (less precise, but no coding)
For a 3 bands spectrum:
- Create 3 game param: Low, Mid, Hi
- For each game param: Set ranges from -48 to 0
- Create aux bus: auxLow
- In effect tab of aux bus, add:
- Wwise Parametric EQ: Low Pass, 200hz
- Wwise Meter: Output: Low
- Wwise Gain: Full-Band Channels: -96
- Create aux bus: auxMid
- In effect tab of aux bus, add:
- Wwise Parametric EQ: Low Pass, 1000hz, High Pass, 200hz
- Wwise Meter: Output: Mid
- Wwise Gain: Full-Band Channels: -96
- Create aux bus: auxHi
- In effect tab of aux bus, add:
- Wwise Parametric EQ: High Pass, 1000hz
- Wwise Meter: Output: Hi
- Wwise Gain: Full-Band Channels: -96
- Send your sound to 3 aux bus: auxLo, auxMid, auxHi
Then, monitor the game parameters from Wwise directly, or using AK::SoundEngine::Query::GetRTPCValue.