Noah, I don't know about the technique others use to remove chest resonance but one thing I find helpful is tilting my head back, so I'm looking at the ceiling, then swallow, you'll notice your voice box get very tight in this position. This is how you need to hold your voice box, it limits the vibrations to the upper throat area as opposed to the chest. Next you just need to raise your pitch. Not by much, just a little combined with a tightened voice box seems to do the trick. In the last few months I've been doing a lot if speaking in front of groups of people, without a microphone. This has been a really awesome "sink or swim" type training situation. I'm not saying "my" way is the right way but, it seems to work without any trouble at all.