A simple and easy to use .PAC archive editor; because one didn't exist previously.
Some of the Shadow The Hedgehog files use a non-default audio format for wav files. I don't know the format, it doesn't appear well documented and thus no support is provided for decoding/converting it.
For those files that exhibit this, simply converting the WAV file extracted from PACTool with FFMPEG or a capable audio converter should suffice and give you a correct sounding audio file.