Run all maint on the PC itself, start with defrag.
RE-record one of your AA prompts, and see if re-recording will fix them first.
If WAV files play fine over speakers or headphones on PC, and this issue is a constant issue via phones, RE-install the current version of VMPRO server.
I assume you know how to export call flows, back up needed WAV files for restoration. After backing up WAVS, take them to another PC, and try to play them, if they are still garbled, you will probably have to start over recording all of them.