I just came back from a business meeting at which time at been set aside to tell jokes, and the twenty-some attendees were in a jolly mood! However, there were a number of people who had difficulty with hearing, and when one man stood up and started his joke very, very softly, a member spoke up and asked him to please talk louder.
Well, the outcome was less than satisfactory! In response, the man, who had a very resonant (and beautiful) natural voice literally shouted his next sentence.
You could see people cringe, and one woman sitting close to him spontaneously clapped her hands over her ears.
(Not something one normally sees during a business meeting!) Joke-teller would start a sentence with a shout, then dwindle to a whisper--then when he remembered to talk louder, he'd blast us again.
We'd cower again.
It was like listening to a high-volume television which got muted every few seconds.
Blast, whisper, blast, whisper.
And the audience cringed, strained to hear, cringed, strained to hear...
The joke was a long story-joke, building up suspense to a great punch line.
Can you guess what happened? The penultimate sentence was yelled, but the punch line dwindled away to a whimper.
The laughter was subdued, to say the least, and the jolly mood of the group was broken.
When you're speaking, people, take care of your audience.
Learn to modulate your voice so that people can enjoy listening to you and can hear--really hear--the point of your message.
Then all the good work you've put into your speech preparation can be appreciated.
And you can feel pleased with yourself!