Files from the pff have to be ran through the extractor tool found in the unofficial mod tools.
https://novahq.net/clicktracker.php?Item=Files&ID=336
The link doesn't seem to be working on my end. not sure if it's just me. I attached them to this reply in case the link doesn't work.
Run the BFC1Extractor.exe and click on the .wav file. After that you should be able to open/edit them. with the BFC1Extractor.exe you can highlight multiple files, but I've found if you try to do too many at once, it will crash.