If you want to speak for true leadership, you need to know how to use your voice. (To learn how to speak more memorably, download my free cheat sheet, "4 Characteristics of an Influential Speaker.")
As self-evident as voice as one of the key leadership skills seems, the truth is that few communication tools equal your voice in terms of both subtlety and impact. Capable of fine gradations as well as the sound of command, your voice can persuade, cajole, enthrall, intoxicate, and accomplish a host of other effects. Using it without understanding its true worth is like hammering a nail in a wall with a diamond: the job will get done, but the beauty and brilliance of the tool will be lost.
To use this component of leadership appropriately, familarize yourself with the following three vocal attributes. (And acquaint yourself as well with the "5 Key Tools of Vocal Dynamics.") Every speaker should employ these elements, but they are crucial to communicating for leadership.
1. Balance. Among the voice knowledge actors learn but business professionals are rarely exposed to is the concept of balance. When the human voice is produced it resonates, i.e., it is amplified in the body, the way a musical note echoes behind the sound hole of a guitar. While there are a number of resonating chambers in the body, the most important are the oral cavity and the chest cavity.
A well-placed voice achieves a balance between those two chambers. A voice that becomes trapped in the head only is called a "head voice"; and one that sinks into the chest is known as a "chest voice." Too much of one without the other creates an imbalance in which certain characteristics are overly dominant. A head voice may sound bright and intelligent, for instance, but young and inexperienced; while a voice sunk in the chest can come across as mature and wise, though stuffy and unspontaneous. Listen to yourself until you achieve a head-chest balance.
2. Strength. More than simple carrying power resides in your voice. It embodies the totality of who you are and what you represent when you speak. In today's business and professional worlds, too many speakers "shrink" themselves along with their influence because their voice lacks strength.
Note that the sentence above wasn't written "the voice is too weak." The critical component here isn't volume but character. Partly to blame is the talking-head syndrome. In centuries past, we had to speak to others across a field or a yard, or in an open-air marketplace. In the age of the microphone and smart phone, what we say is often too small. Practice bringing your whole body into play when you produce sound. Pitch the volume correctly, but allow your voice to possess strength.
3. Control. Leaders speak with complete control, and the let the rest of the world serve lesser masters. Many presenters, for instance, follow their information— they believe that delivering information equals effectiveness. Others fight for control but never fully achieve it (people with speaking anxiety are in this category). And still others aim to survive a speaking situation, and so never understand the value of exerting control.
Instead, your audience needs to see and hear you as a leader. So your pacing, silences, emphases, pitch inflection, changes of vocal quality, passion, excitement, emotions, and other vocal attributes need to come through. A speech is as much a performance as any on a Broadway stage or screen at the multiplex. Work on whatever allows you to speak at this comfort level. That's when you'll be speaking with the true voice of leadership. 
