Slow things down.
Give yourself plenty of time to form the words loudly and clearly enough so the person next to you can hear you.
This also gives you that advantage of being able to think while your speaking which improves what you say.
And it also gives you the advantage of appearing more powerful and confident.
The record voice natural cuts out alot of the speakers energy (hence why some people have more energic phone voices). So practicing with a voice recorder could of benefit.