Size of the vocal cords isn't the only factor. Just like with string instruments, the same physical rules apply.
* Longer cords are deeper
* Thicker cords are deeper
* Cords under less tension are deeper
A taller person will usually have longer cords, but just like some little dudes have big hands, it's possible for a little person to have long vocal cords. It depends on how their own body dimensions work out. Also, even if you have short cords, they'll produce a deep sound if they are especially thick. The thickness of the cords is mostly determined from how your body responds to puberty. And vice-versa, someone with long cords can still have a high-pitched voice if the cords are relatively thin. Finally, people with more relaxed vocal cords have lower-pitched voices, and people with more high-tension cords have higher-pitched voices.
