A couple of years ago I got Silent Hill 1 for PS1, and I played it on my laptop thanks to the ePSXe emulator. I found something weird about the game: in the dialogue sequences there was no speech, I got the subtitles and the background audio but not a simple word from the characters. I believed it was a configuration problem but I played Resident Evil 3 and Dino Crisis 1 recently, with the same emulator settings, and I got the dialogs voices. So, is this a problem related with the silent Hill I have or there are no voices in the dialogs?
There may perhaps be an audio issue with the ROM file you are using, which you can't do anything about. From my personal experience, I have played Silent Hill 1 on my PC using ePSXe also and experienced similar issues as well.
I remedied this by forcing the audio codec to a different option than what was selected as default.
Hope this helps.