The sound files used are called (wwise) soundbanks or short "*.bnk" . Wwise is a programm by Audiokinetic and is a professional tool for creating soundeffects and music for cross-platform games. This means it is a very powerful tool, espc. with its SDKs and addons. However, this also means it is fairly complex and "just converting a *.wav or even *.mp3 to *.bnk" is NOT possible (mp3 not supported, but there are good reasons for that). The reason is the way a *.bnk sound file saves information about various effects and not just the audio part, so it is easily used inside an editor.
Information about Wwise:
https://www.audiokinetic.com/products/wwise/FREE license (slow) download:
https://www.audiokinetic.com/downloads/If you want to get into creating *.bnk files check the TUTORIALS on Wwise:
https://www.audiokinetic.com/resources/videos/Regards,
Chris
