I know that giant with a booming voice is pretty classical but I don't see why dwarves voices should be short-ranged. Kid's voice sure carry afar. A few years of singing opera would increase your range more than being giant, imho.
I was thinking about this the other day. My conclusion was that since you (more or less) double/half height every +3/-3 points of Size (see "How Big is a Giant", page 84, RoP:M), I'd loosely rule that your Voice range doubles/halves for every +3/-3 Size above/below 0. So between Size +2 to -2, no appreciable change in Voice range.
I'm speaking in term of mechanics of game. Yes, the virtue large has no effect on the voice. Rob Ford is a good example for this: he's large (size +1), but not big enough to merit a size +2. So no change for his voice.
Well, theoritically, it should double the voice range by change of size category. I agree with this. But it should begin at size +2, since the voice range is for size -1/0/+1.
I always took those distances to be more to help people get an idea in their head than hard and fast limits. If my Failed Apprentice wants to stand outside of the range of a Voice Range spell, he is not going to plan to stand 55 paces away, he is going to plan to stand further away than he thinks a voice would carry. I am not sure how translating it into paces helps.
Googling “Loudest Animal in the world” doesn’t seem to show any correlation between size and how loud something is. Howler monkeys can be heard for 10 miles and a lion only 5 miles away. I have seen parrots who are louder than any person I have ever met.
OK, so now I am thinking of a Bjornaer with an African Grey Parrot as a Heartbeast.
Well I'm not sure I'd connect it with giant size Booming Voice might be a fun virtue in it's own right. Not only do you get an increased voice range but you might also get a bonus to different pre and com rolls in applicable circumstances.