Form and function are strongly correlated. Ceteris paribus, a large muscle is stronger than a smaller one. It therefore stands to reason that a person with a larger Broca's area will speak more fluently than a person with a smaller one.
A problem for the experimental neurolinguist is figuring out how to enlarge Broca's area. It is a well-known biological fact that striking a person with a rock induces swelling at the point of impact. We decided to try this approach.
Difficulties always encumber innovative research. We wasted our first five subjects by hitting them too hard. After lengthy hospital stays, they are recovering nicely.
After that, the university cut our funding. They claimed we were damaging the university's image. If memory serves, the Dean of Theology at the University of Wittenberg said the same thing upon publication of the 95 theses.
Luckily, the California Highway Department is not so unenlightened. With their aid, we were able to continue the research and keep making payments on our nice, split-level, ranch-style homes. The results were as follows.
When you hit a subject hard enough to rasie a lump on the head above Broca's area (but not so hard that you knock the subject out), the subject typically responds with a vocalization at a much higher than normal volume level. Furthermore, such vocalization is usually followed by a loud and rapid speech stream in which the speaker directs voluble imprecations toward the research team and/or fervently pleads to be released from the experiment.
In sum, the research fully vindicated the initial hypothesis. Having a larger Broca's area makes you talk louder, quicker, and more.