Unless you are doing some type of surprise or big rah rah opening in your
public speaking engagement, consciously start out with a slightly lower than
normal voice inflection. In the excitement or nervousness that many of us feel
at the beginning of a speaking engagement, it is easy to go the other way and
start out with a voice inflection that is too high. The problem with this is
that if you are already at a high range when you start, you have nowhere to go
as you attempt to crescendo the audience to a big peak of excitement at the end
of your program. Consequently, you would have already
reached maximum voice "headroom".
When you present in public . . . start low.