I hate when that happens...
First thing to check, look in sfc.ini in the main program directory using a text editor. It is a text file.
Look for "voice = ?", where ? is a number (probably 0 if you are hearing no voices). To get maximum crew feedback, set voice = 3.
If that was the issue, make sure that sfc.ini is write protected and make a back-up of the file somewhere safe. It's just a little file, but it impacts some very important stuff.