Each version of this integration matches a specific build of Unreal Engine 4. Here is what has changed between the 2017.2.1.6524.866 and the 2017.2.2.6553.895 release of the integration (in addition to upgrading to the new Unreal build).

Unreal Engine 4.17/4.18 - Wwise 2017.2.2.6553.895

• WG-35044 Made the behavior of overlapping reverb volumes sharing the same Auxiliary Bus more deterministic.
• WG-36335 Removed unnecessary logs.
• WG-36369 Added missing include in AkAudioDevice.h.
• WG-36429 Replaced LoadModuleChecked with GetModulePtr in FAkAudioDevice::Init().
• WG-36494 Made FAkAudioStyle into a singleton to avoid a non-editor crash.