I don't speak Japanese, but I notice in some manga (like Mr. Fullswing for example), male characters tend to scream "gya" or "guwa" while female characters tend to scream "kya".
Is it true that "gya" sounds masculine and "kya" sounds feminine? If it is, what makes "gya" masculine and "kya" feminine? Is it common practice to use these interjections as such? If a female character uses "gya", does she tend to be describe as boyish (using "ore", "boku" and whatnot)?