Let me briefly discuss the significance of your question then give a few suggestions towards making your voice louder and clearer.
There are several studies of interest that highlight the importance of voicing.
In one such study, conducted at UCLA, Dr. Albert Mehrabian found that when verbal, vocal and visual signals are inconsistent, content counts for a mere seven percent of the overall message. In such a situation, 55 percent of the message is transmitted by facial expression and body language; and 38 percent comes from voice quality, pitch, tone, volume, and inflection. He also found that when talking on the phone, the actual words you use account for only 16 percent of the way you and your message are perceived. The remaining 84 percent of your impression depends on the sound of your voice and the feelings people get when listening to you. There are several of these types of studies that have verified Dr. Mehrabian's work.
As for general agreement on the importance of voice, check out this link; Many wish they had a different voice.
It says that "the eyes might be the mirror to the soul, but what your voice sounds like is apt to make a first impression--good or bad. A survey conducted by Harris Interactive on behalf of the Cepacol line of sore throat-soothing products found that 21% of adults feel a person's voice is as important as his or her looks, while 17% maintain that an individual's voice indicates how educated he or she is. Moreover, 16% of people wish they could alter their voice in some way". So we see that our voice is our very important tool.
My first suggestion is to find and read a book like; Speak to Influence,
by Susan Berkley [the first chapter is available; on-line
]. Like all books, it has a few critics, but my belief it is a good place to start; it has helped many. And for sure, we are after what others have done to improve the voice, so turning to a good voice coach or speech-language pathologist is the goal.
I suggest reading how others have found their public voice.
In doing so you have opportunity to separate your voice [the self evaluations of your voice
] from the task of speaking. For example, this simple article; How I found my voice,
(techniques of speaking articulately in public)(The Perfect Man - Esquire) tells how one man found that animating his voice created a voice that the crowd liked. A highlight of the story comes after the author's first success; "the referee, Joe Cortez, came over and put a kind hand on my shoulder. 'You did really good,' he said. 'I was there on Michael Buffer's first night, must've been fourteen years ago, but I'll never forget. He introduced me as Joe Ortiz. Now look at him.' Cortez whistled admiration through his teeth. 'Don't kid yourself, though--he worked at it.'" In context, this evokes an encouragement, that they those around us, will mainly remember how good we are today. Most will forget our start. In other words, when we learn to speak loud and clear we will be remembered by the fact we speak loud and clear.
Here's a link; Making your speech memorable,
(preparing effective speeches) (Leadership - CWI). This lengthy article offers much of the same advice given in this forum. As for voicing, it suggests you "animate your voice. Altering the intensity and level of your voice not only keeps the audience interested but also provides them with audio cues to your important points. And take note of the different voices you use during a typical day, and incorporate that variety into your public speaking. For example, you probably sound very different when running a board meeting, making a presentation to a potential client, relaxing at home with your children, and conversing with your spouse. Vary your pacing and your pitch, inserting into your formal speeches the same 'peaks and valleys' you use in everyday conversation". The point is, that we can use our voice as a tool. I again suggest a degree of separation from our voice; I am not my voice, my voice is my tool to speak.
There are many other links of interest.
You can find the subject covered for actors, leaders and even the transgendered; they all give clues on how to master the voice [how to take control]. Read how some practice speaking by walking along the beach and very loudly speaking while others place pebbles in their mouth and speak for clarity. There is a good practice of speaking while holding a mirror; such that you only see your mouth. Your visual system will more quickly help you change the movements of your mouth so that the words are clearer.
To test progress, some suggest leaving yourself phone messages.
Your voice will sound different than you expect, but listen for its clarity and crispness. Practice.
Hope this has helped.