A SoundBankDef is simply a list of [SoundCollectionDef][]s to load. Each [SoundCollectionDef][] will be loaded only once, so there is no need to worry about specifying a [SoundCollectionDef][] in multipleSoundBankDefs. SoundBankDef`s allow you to decide how much memory you want to devote to audio assets and manage groups of them together.