"If there are UI sounds that are consistent across the two scenes, is there a way to load it once in the main menu and keep them loaded in the gameplay scene"
- If you load your SoundBank in the Main scene, and don't "unload" it when loading another scene (see Unload On: property in your AkBank script), you can keep playing UI sounds. So if your Main scene is always loaded, you can add the AkBank to it and your Main SoundBank won't unload until you exit playmode (if the Unload On. property is set to destroy).
"What would be the best way to load a soundbank that will be accessed through multiple scenes?"
- Like above, SoundBanks stay in memory until you unload them.
"would I have to load that soundbank whenever a scene is loaded?"
- A note that might be worth mentioning, is that Wwise has Media Relocation.
This means that if you load this ...
# SoundBank 1: (Shotgun sound, Forrest Ambience)
... and then load ...
# SoundBank 2: (Shotgun sound, Desert Ambience)
... the Shotgun sound will not be loaded twice, and avoid that you use double the memory for it.
Result:
# Memory: Shotgun sound, Forrest Ambience, Desert Ambience.
The same applies the other way around, so if you unload Soundbank 1 from memory now, Wwise would see that another SoundBank is using the Shotgun sound and therefore not unload it.
Result:
# Memory: Shotgun sound, Forrest Ambience.
Let me know if this helps.