Music & Sound Modding - ArthurHeitmann/F-SERVO GitHub Wiki
You can find sound files in .bnk files (inside .dat files) or .wsp files ([NierAutomata]\data\sound). Sounds in BNK files are usually short sound effects that are frequently used. WSP files contain music and voice lines.
Inside of these files are .wem audio files. F-SERVO can play .wem files or convert them to .wav. Alternatively you can play .wem files with foobar2000 and the VGMStream component.
To replace .wem files you will first have to install Wwise 2014 and set the path to it in the settings, as described here. The process for replacing the .wem files is different between BNK and WSP files. BNK files are relatively simple container files. WSP files however are managed by a single WwiseStreamInfo.wai file.