Misdirections of airflow and information

I've always had a problem with being quieter then I should be. It shows up when I'm talking to a couple hundred people and just can't raise my voice enough to be heard properly.

Now, if you've ever had that problem, or been around someone with that problem, or had a reasonably well-rounded education in public communication, you have probably also heard the advice to "speak from your diaphragm". The diaphragm is the muscle underneath the rib cage, and you can project your voice farther if you clench it as you expel air, rather than contracting your rib cage. Most people tend to speak from their chest instead of their diaphragm back when they're poor uneducated souls, blind to the mysterious ways of the public speaker. If you want to check which one you use naturally, try breathing normally while resting one hand on your chest and one on your bellybutton. If the hand on the bellybutton moves, you're a diaphragm breather.

I, unlike most people, speak from my diaphragm naturally. I never had to change when I started public speaking. I'm pretty sure that's why I have a hard time speaking loudly. I'm used to speaking normally, while still using my diaphragm, so concentrating on using my diaphragm doesn't help me project louder than usual. Recently, I've realized that I actually can speak about as loud as I want if I contract my chest and lungs along with the diaphragm. Apparently, it's a combination of the two areas that really projects. Go figure.