The japanese version has many more speech files than the english version does. If not close to double the amount of speech files.
The majority of the JP speech files once rebuilt into an archive are:
Missing
Differently Named
Etc.
**This is why it is silent when the files were incompatible between both versions.
It took me many months just to get the subtitles to load correctly with the modified speech files. In many different previous iso versions the mod would produce subs that had a mix of JP and ENG including funky ascii. Also previous versions had issues with crashing.. Once I finally figured out howto swap and mod everything that was possible then rebuild the archives correctly, the final result is that some of the FREE speech is silent.
Free Speech has close to 60 percent complete undub.
Cinematics is more like 98 percent complete undub.
Anyhow it was a complete bitch to mod undub.
The project is complete..although Revive DC will someday do a repack for Disc 3.
Consider this undub a hacked undub. (Modified Files, Swap, etc.)
Play this version until a newer one is available...
The only way that a 100 percent complete undub can be done is if the subs are translated from japanese to english. (while using all the jp speech files)
Good news, Kogami is doing this exact translation of Shenmue 1 for DC.
Some day it will be complete and you will not have to play this version anymore.
Hope this helps.