Granted this is only a tenative hypothesis, but thus far the logic behind it is sound. I believe I may have found an explanatory mechanism behind the trend of the loudest members of our species frequently being the most moronic.
I believe it is becaus of thus: the louder member of our species are the ones who are more naturaly inclined to be idiots. Therefore they are more likely to put their foot in their mouth. Each time they do this they stretch ouh their mouth by a small but noticable margin.
Each time they stretch out their mouths, they increases the resonance capability of their mouth, thus making them slightly louder. The louder they get the more people they can effect with their idiocy. Thus further increasing the number of times they are able to shove their feet into their mouths, further stretching it and further increaseing the size of the mouth as a resonating chamber.
We quickly find that such individuals create a vicious circle for themselves, thus quickly making such persons the most vocal and, much to the chagrin of the rest of the populace, most aggitating members of our species. I believe the only way to resolve this self perpetuating cycle is through the long duration administration of education to lessen the individuals foolhearty behavior which would hopefuly begin to slow down and/or end the cycle. If the treatment is delivered soon enough, the symptoms may even be reversable. Although in seveare cases, such methods may be offered too late in the patients illness to provide any noticable effect. In such cases it is my advisment that the only way to prevent such further behavior (as well as lessening the ambient noise level around them) is to fit the patient with a proper fitting muzzle and/or gag. The usage of behavior correcting tools such as shock collars may also be necessary.