No advice sound and sound in preview clips

Hi I have just got a new computer and installed Napoleon. The problem I have is that I get no advice audio or voice audio in the preview clips ( eg the one before waterloo). I have sound for other areas including music, unit voices, cannon etc... Even the voice of napoleon during the game start up video.

So I'm not sure what to do. I tried device manager and search for new drivers for audio, but it says latest already installed.

I have onboard sound from the ASUS AM3 M5A97 R2.0 motherboard.

Driver details:

Realtek High definition audio
driver date 07/08/2012
Version: 6.0.1.6699

Any ideas? Thank you

To clarify No advice voice audio during the battle. Just the text in the corner. And no voice sound during preview audio in the movie clips before battle, just have the music and the text.

Thanks

Check your battle audio settings?

Its not that, as I'm hearing the units fine. Also There should be speaking in the videos beforehand, whatever the battle settings