@Ao:
Weird voices sound more distinct or have way more distinct pitches to hit than normal sounding ones. I can do a spot on-PERFECT Golem from LOTR, but ask me to do a Frodo…
That's what I mean. The odder sounding the voice, the easier it easy to mimick. End of Explanation.
Usopp's voice may be distinct, but he also requires the largest range.
As opposed to characters like Zoro and Robin, and Nami to a lesser extent, who don't really change their tones very often, or even Luffy and Sanji, who stick with a couple different tones, Usopp is all over the damn place.
Zoro's easy. Sound various levels of angry depending on the situation. Usopp has to be scared one minute, thoughtful the next, brave after that, nervous after that, angry after that….
Mayumi Takani's Luffy does have a raspiness to it! She sounds like an actual kid,but her voice overall is kinda a throaty raspy female voice which is why she's always chosen to play ultra tough females or young boys in the first place.
Going back to this…. Takani's Luffy has always sounded to me, the voice at least, more like one of those little old happy men. Like a less exaggerated Kumadori. Especially when he laughs or sings.
I don't know about her other roles, but she uses the same voice for Luffy as she does for Koenma, a character that actually is supposed to sound much older than he looks.