Thanks to Winfrey and Lanlynk I now have voice!
The GOG link said the problem was with the soundcard, not the program. I don't know how to update my audio drivers, so I experimented. The audio properties menu said that my output was Realtek Audio rear speakers. I have 5.1 sound. So I tried resetting them to Desktop Speakers (2). This fixed the problem and I have full sound now. I'll change it back when I'm not playing. Thanks so much to you both. I did not have a clue what the problem was.