Each version of this integration matches a specific build of Unreal Engine 4. Here is what has changed in the Unreal Engine August 2014 release of the integration (in addition to upgrading to the new Unreal build).

August 2014 - Wwise v2014.1

• UI-166 Fixed: Auxiliary Bus properties are now applied on Ambient Sounds contained within Reverb Volumes.
• Updated Wwise version to 2014.1. If you wish to keep on using 2013.2.x, see Frequently Asked Questions.