Peter,
Sorry it took a while to respond. In the menu you should select Manual audio settings.
Take a look at Canon's website. It has a great description.
http://www.usa.canon.com/dlc/controller?act=GetArticleAct&articleID=3287
Hope that helps.
Ed
Avid and FCP Preditor
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Anything worth doing at all, is worth doing well.
- Philip Dormer Stanhope, Earl of Chesterfield