Each version of this integration matches a specific build of Unreal Engine 4. Here is what has changed in the Unreal Engine September 2013 release of the integration (in addition to upgrading to the new Unreal build).

September 2013 - Wwise v2013.2.1

• Fixed build settings for Visual Studio 2012.
• Fixed UEngine::UseSound() returning false when only AkAudioDevice is present.
• Fixed crash in UAkComponent::PostAkEvent with null event.
• Fixed game object position with static actor.