An article from LawCrossing that just might help advance your career:
"You have probably heard the cliché 'You get one chance to make a first impression.' You have probably also heard that while your words only communicate about 7% of what you are trying to say, nonverbal cues communicate the remainder of the message you are sending.
"While a large portion of this remainder category includes body language, a significant amount of your message is conveyed by your tone of voice [PDF]—the way that you speak. The manner in which you speak can contribute either positively or negatively to a listener's perception of you.
"In her book The Gentle Art of Verbal Self Defense, linguist Suzette Haden Elgin states that a lower-pitched adult voice is more acceptable in our culture than a higher-pitched voice. Another characteristic of tonality that is perceived negatively is pronounced nasal quality. So if you speak in a high-pitched, nasal voice, you may be in danger of projecting a less-than-professional image. In the words of Elgin, 'if you sound like a child, you will be treated like a child.'"