I always question why those who are either already speaking professionally or planning to do so, are not aware of the vehicle for their speech or presentation. It is called the speaking voice. Without it, they would have no career. Just ask Tony Robbins how important his voice is to him and what 30 years of talking without proper usage of his instrument has done to his throat and voice box! It is called vocal abuse; and, in his case, it is severe and permanent.
I liken public speaking without voice training to the doctor who never studied biology or the minister who is not familiar with the Bible. The vehicle for the doctors is their knowledge of the human body; the vehicle for ministers, on the other hand, is their knowledge of Gods word.
While you may believe that the microphone is going to solve all your problems on stage, you are mistaken. Microphones do one thing and one thing only. They amplify. If you have a wimpy sounding voice, the microphone will give you a louder, wimpy voice. If you already speak loudly and have any type of shrillness to your sound, the mic will make you that much more shrill. If you sound like a child, the mic will only serve to make you sound like a loud 6-year-old!
If, on the other hand, you find that you are hoarse or experiencing a sore throat after speaking for 50, 90 or 120 minutes, then it is likely that this will happen every time you talk for any great length of time. Again, it is called vocal abuse; and, unless you change the way you place your voice, it will only get worse.
Voice training has many, many benefits for the professional speaker, not the least of which is the prevention of vocal abuse. Beyond that, however, is the ability to discover your real speaking voice. Powered by your chest cavity instead of just your throat, voice box, mouth, and nasal cavities, the voice that makes use of the chest cavity will be deeper in pitch, resonant in sound and more mature in quality.
In addition, a voice being powered by the chest cavity can be amplified easily without shouting. It is called projection; but, it is only possible if the chest cavity is your primary sounding board.
Imagine discovering a richer, warmer, deeper voice that can truly captivate your listeners while preventing vocal abuse in the process. If you are planning a career in public speaking, look for a program that will show you how to find your real voice. Its in there. Its just a matter of discovering it!