IPhone 5 drops audio


I have an Phone 5,not jailbroke - latest software update.

I listen to audiobooks. As I am just sitting there listening I sometimes play a game at the same time.

Everything has been fine but it just started dropping the boo when I start the game. Is there some setting I have screwed up? It worked fine and now ......

I know the cpu can multitask so it should work and has in the past.