I've tried every suggesting involving compatibility mode, editing the compat.ini (m_bDSoundLocForceSoftwareOn) and nothing is fixing the Voices being cut off. It happened in BS1-3 but not to this extent. It's unplayable without subtitles and annoying with them on.

There has to be a way to fix this. Anyone? Windows 10 if it matters.

The solution involving the compat.ini file requires the change of both these values: Anyway, another solution could be to add the "-compat-on" parameter to the game's executable.
Right click on the game's shortcut, click on Properties and select the Shortcut tab. Add "-compat-on" (without quotes) at the end of the Target box, after the last quotation mark. Apply then run the game.

Doesn't help. The speech continues to be cut off. Honestly I was tired of tearing my hair out so I'm living with it. Very badly designed game in terms of the technical side. Seems theres a visible 'skip' when the audio issue occurs. I can always predict when it happens, so I read ahead.

Then we have the 3D memory leak. If you stay in large areas too long the game slows to a massive crawl. Exiting and restarting the game fixes it.

Have you tried editing the ini file and adding the parameter together? Maybe using a compatibility mode too? I am not sure, but performance issue could be related to multicore CPU too.
Try editing the file custom.ini. Locate these lines: Change 0 to 1 and save the file, then run the game.