"What is the most important thing to remember when you get up to give a speech?" Here are a few common answers.  
      "Have lots of slides, so they won't be looking at me all the time."
      "Don't forget my notes."
      "Wear comfortable shoes."
      "Make sure they can hear me."

      There are probably as many answers as there are public speakers.  Here's mine: Most important? That the audience hears me and understands what I'm saying.
      The primary vehicle we use to make sure they understand us is, naturally, our voice. How we feel about giving the speech will influence how we sound when we actually begin to talk.

      When you're feeling good about yourself, confident that you know your material and will do a good job, the tempo and tone of your voice will show it. You'll speak with good volume, at a speed that's easy to listen to, not too fast, not too slow. You won't suddenly lose your voice and speak in a whisper or talk too loud to cover the sound of your violently beating heart.  Your voice will sound regulated, even and strong. They'll have no difficulty understanding every word you say.

      But what if, when you get up in front of the room, you speak too fast, too slow, too loud, too soft, in a jerky uneven tempo, or even feel like you're losing your voice in the middle of your talk? Here are a few reasons why that might happen:

      Too fast? Your mind works faster than your tongue. You have too much to say, not enough time to say it and you're really anxious to get it over with. Perhaps when you were a kid expressing your opinion, you were told to be quiet, what you think doesn't matter. You got into the habit of speaking fast to get it all out before they could shut you up.

      Too slow? Are you unsure of what you're saying. Worried it's not 'right'.  Maybe as a child you were told to slow down, you're talking too fast.  Speaking slowly became a habit. Or, perhaps you're afraid you didn't prepare enough material to fill the time you've been given.  Suggestion:  Rehearse with a timer beforehand and you won't have to worry.

      Too loud? You're afraid they won't listen unless you're extra forceful.   Did you have to compete for attention when you were growing up and speaking loudly was the only way to be heard over the others?  Are you're afraid the audience will fall asleep? You may have a hearing deficiency and don't realize how loudly you're speaking.

      Too soft?  Are you sure of your material?  Worried you'll say something they won't agree with? You don't want to be heard because then you'll have to defend what you're saying. Maybe you're shy and embarrassed to be in front of people because you don't feel you belong there?  

      Jerky tempo? Lots of starts and stops, you can't get a smooth rhythm going? You're probably not sure of your material. Can't find your place in your notes, or you're trying to 'wing it'? Rehearse ahead of time instead. Trying to make it up as you go along is a fool's game. 

      Losing your voice? Are you so disheartened by your incompetence that you don't even want to be heard? Creating an excuse to end your misery quickly? Or may be you really are coming down with laryngitis.

      Your voice will tell your audience that you're feeling absolutely competent and sure of what you're saying. Your vocal confidence will let them know that what you have to say is worth remembering. They'll pay attention and listen carefully because they know they'll learn something valuable from you.