I'm a native English speaker living in Tokyo, and I recently went to an event featuring a moderately famous bilingual (English and Japanese) actor (he's Japanese, but his parents moved to America when he was in late elementary school, where he lived in the West Coast until he graduated college, and now he's back in Japan). A few members of the (almost entirely Japanese) audience asked him to say a few things in English, and when he did, he made the observation that his voice was quite a bit lower when he spoke English than it was when he spoke Japanese, though he didn't think he consciously made it that way.
It made me realize that I do exactly the same thing--my voice is quite higher when I speak Japanese than when I speak English. Is this just a quirk, or is it something commonly observed in speakers of multiple languages? Any explanation for it? Me being a girl and him being a guy, I didn't think it had much to do with gender stereotypes, especially as he hadn't spent nearly as much time in Japan as in America (but his Japanese is still perfect), and I've spent far less time in Japan than America.