Loss of voiceover in cutscenes

I am experiencing frequent (inevitable) loss of voiceovers and sound effects in cutscenes.

I will have speech initially (eg main quest lines) but as soon as the game loads the next set of data, all main sound effects are lost - speech and effects. I still retain ambient sounds.
Alt-tab switching also appears to cause the effect.

Other system sounds remain intact throughout.
I have my system set to headphones (2 speaker sound).

Googling the problem I notice this appears not to be an isolated problem but I cannot find a solution.

Thanks in advance for any help! :D

There are more than a few cutscenes that start with voice acting, but then change to just text after some introductory lines. The Envoy quests, for example, have a few initial lines from the city leaders spoken (Along the lines of "Greetings, I am NameX the RankY of CityZ. What news have you from CityW?") and then everything else they have to say is text only.

So my guess is that things are working as intended for you, it's just (imo) an odd design of the scenes.

Thanks for the reply, however I'm still fairly certain it's an issue.

For example, the entire Ifrit cutscene was entirely silent (save for a pleasant background ambience which didn't quite fit with a demon roaring fire circles!)

I'll bear it in mind and see if it makes sense though.