Before amplifiers, if you wanted to speak to a large group of people, you had to project. Even now, singers and actors still use it because projecting not only allows one to sound relaxed at higher volumes, but also improves control and reduces strain. By projecting, they can get as loud or quiet as they want, and have the sound of their voice remain consistent.
Projecting depends on the combination of two separate skills: enunciating and speaking from your diaphragm. I emphasize speaking because projecting has absolutely nothing in common with yelling. Those with theater experience already know what I'm talking about. For the rest of you, try the following experiment.
Let's start with yelling. In a reasonable private place (a car with the windows up works well) try slouchng forward, slumping your shoulders, bowing your head, and yelling as loud as you can, "This is yelling!" If you did it "correctly", you probably noticed a few things:
- No Diaphragm - You couldn't take a full breath to yell with and you couldn't use your diaphragm to power you voice, so you had to compensate.
- Straining Vocal Cords - Your voice sounded (and maybe felt) tense and strained, and you might have felt pressure in you neck and head.
- No Focus - you're creating a lot of noise, but it's not really going anywhere. By looking down, you direct your voice into the ground muffling it.
That's yelling. If you do that too much, your vocal chords swell from the strain and injury, and you'll loose your voice until the swelling goes down. Do that repeatedly and the quality of your voice will change permanently. Now try standing (or sitting up) straight but relaxed, holding your head upright, focusing your eyes straight ahead, taking a deep breath, and saying, "This is talking." Next, imagine you're speaking to somone ten meters away. Changing as little as possible, say, "This is projecting." In this case, "correct" will have different characteristics:
- Diaphram - You'll feel a tightening of the muscles around your midsection and ribcage as your diaphragm acts like a bellows.
- No Straining Vocal Cords - Your voice probably sounds different than normal, but not tense or strained. You should feel no pressure in you head.
- Focus - by facing forward and picturing a target, you give your voice somewhere to go.
Now you're "speaking from your diaphram". Next, try enunciating - exagerate the movements your mouth and lips to fully and separately form each word. Enunciation will keep your speech clear over longer distances, compensating for the muffling and/or echoing effects of various objects in the area. To begin with, you'll need to speak quite bit slower and your face will get tired rather quickly, but experienced orators can enunciate at normal speed and even faster.
Put these two skill together and you have projecting. With practice, projecting will enable you to do things not possible with "normal speech". On the quiet side, you have "stage whispering". Keeping your focus distance the same but lowering your the volume, what you're saying carries but sounds like whisper, allowing you to say something "under your breath" that you actually want everyone to hear. On the other end of the spectrum, there's "bellowing". Again, keep your focus at the same distance while increasing your volume until your voice just begins to strain like it does when you yell. Above this point, the danger of vocal chord injury increases dramatically, but at or below it you can still reach startling volume levels. Concentrating all that volume into a short violent outburst, such as the "kiai" used in various martial, can be a surprisingly effective weapon.
Even in normal interpersonal interaction, people who project have advantages. They can get and keep peoples' attention because their voice can fill a space. They can also communicate their message more effectively to a group, sounding relaxed and confident as they speak. Take a look at Cate Blanchet in Elizabeth when she speaks to the lords regarding establishing an offical Church of England. Imagine what would have happened if she had not been able to be heard over their yells or if her voice had sounded strained when she did so. Truly, as Shakespeare wrote, "All The World's A Stage".