If you listen to the files on the computer with ears, your eyes are protected.
Microsoft Text-To-Speech(TTS) voice engine has been installed by default on Windows 2000, XP, Vista, you can find what voice engines have been installed on the computer by following Control Panel->Speech->Speech Properties->Text To Speech tab->Voice selection drop down window. For example, the voice of Microsoft Sam has been installed by default on Windows XP, and Microsoft Anna on Vista, and the voice of Microsoft Anna is of good quality.
I have got
panopreter , now I listen to files with it, it is a free Text-To-Speech application, it also converts files into wave and mp3 files, I think it's better than the Narrator on the Windows XP, when I listen to the audio files, my eyes feel better.