February 2018
Additionally, check that your PS3 audio settings are set to 2 Ch. (stereo)
http://manuals.playstation.net/document/en/ps3/current/settings/audiooutput.html
February 2018 - last edited February 2018
Have you checked under Main Menu ==> Options ==> Audio?
There are four separate settings:
1. Master Volume
2. Sound FX Volume
3. Dialogue Volume
4. Music Volume
Maybe the Dialogue one has been turned down?
February 2018
Additionally, check that your PS3 audio settings are set to 2 Ch. (stereo)
http://manuals.playstation.net/document/en/ps3/current/settings/audiooutput.html