Talking from the diaphragm is an alpha male characteristic. As a matter of fact, singing teachers tell their students to practice this. When originating from the bottom of the stomach, the human voice has more strength and purpose. The voice sounds less confident and flat when solely originating in the larynx.
Call to mind all the men you have ever been around who thrive with women. Ever notice how they talk? A masculine voice is very appealing to a woman. A great way to practice this is to push air from your diaphragm when you speak and breathe. Practicing this strengthens the muscles in your diaphragm and makes your voice appear deep and masculine.
Alpha Male Speaking Traits
When a man says words like "um" and "uh", it makes him sound unsure of what he is saying. If you can avoid these kinds of words, you will seem more confident. Politicians are instructed to do this when giving speeches.
There's no reason to make these simple kinds of mistakes. Rehearse talking into a tape recorder and listen to yourself talk. It can be hard to listen to at first, but practice you will make you sound better and better. Take "um" and "uh" completely out of your vocabulary. Make an effort in all of your daily communication, not just talking to women.
Watch it, speedy
A fast speaking speed indicates a lack of confidence. A slower speaking speed, of course, has the opposite effect. Also, pausing for effect shows high status.
Use a recorder and practice. The recorder never lies!
Annunciation
Don't mumble. When you annunciate, it is clear you aren't embarrassed of what you are saying. This displays confidence.
Practice, practice, practice!
Eye Contact
This is very important! When (not if) you look a woman in the eye when starting a conversation, it is crucial that the woman look away first. I can't stress this point enough. This gets things off on the right foot. Keep in mind, though, there is a fine line between staring and displaying good eye contact. A rule of thumb is to look her in the eyes more when you are talking, and less when she is talking.
I really can't convey to you enough how important this is. If you disregard everything else here, don't disregard this! Fun experiment: The next time you are speaking with a woman you are attracted to, wait for the moment when you and her "lock eyes". Whatever you do, make her look away first! This will have a very powerful effect on her. This also will present a chance to examine her pupils (More on this later). She will start to blush and look down towards the floor (A sign of submission), and maybe even lose her train of thought. She is now in the presence of an alpha male.