Taking responsibility for your vocal  health starts with understanding how the system works. To do that, you  must appreciate the three production steps:  respiration, phonation and articulation.

Simply, respiration is air. You need it to produce the pressure and vibration necessary for sound.  Phonation means making sounds. As air passes through your larynx (voice box), tissues vibrate to produce sound waves. Articulation is the shaping of  raw sound into recognizable speech. Quite cleverly, you move the tongue,  palate and other structures in just  the right way at just the time time  to form words. For simplicity, we will leave out the mastermind of this whole system: the brain. As you explore speech production, though, you will undoubtedly appreciate how masterfully many tasks are be coordinated  --  within fractions of seconds.

Respiration: air fuels the system: Respiration is the body's cyclic intake and exhalation of air. When you prepare to breathe, the diaphragm (the large, flat muscle located below the lungs) drops. This causes the volume within the lungs to expand, and air swoops in the nose or mouth, down through the larynx, and into the trachea, bronchi and, finally, lungs.

Is there is a right or wrong  way to breathe? For professional voice  users (such as teachers), a beneficial  tip is to keep the abdominal  muscles supple and relaxed. This allows the lungs to inflate fully for ample air to support  your speech.

Phonation: larynx sound makers: Most of the time, air swishes by the vocal folds, which remain open (abducted, or apart). To make voice, however, the vocal folds are brought together. When we do speak, it is always on the exhalation of air. As air whooshes by them, vocal folds ripple, snap and hum, not unlike flags blowing in the wind. The faster your vocal folds vibrate, the higher the pitch of your voice. That is not due to the speed of the respiration, but rather to the voluntary shaping of  your vocal folds.

What's in your voice that makes you sound the way you  do?  Is your voice: yawny,  breathy, rough, strained, pressed,  nasal, hoarse, pulsed, resonant, or tremorous?

 Voice qualities are based on:

• How tightly we close the vocal folds: loosely fit vocal folds create a breathy sound.
• How symmetric the vocal folds are: out-of-synch vibrations result in a creaky, froggy or rough voice.
• How much muscular tension presses  the vocal folds together: excess tension  produces a strangled, strained or tense  voice; too little produces  a weak or dull voice.
• How the vocal tract is shaped and how freely airflow moves: certain configurations help the voice "ring."
• How balanced the air emits from the nose and mouth: excess air out the nose sounds nasal.

For most of us, our voices are melting pots of different qualities in various amounts. When you factor in other features (like pitch) and speech traits (such as rate and rhythm), is it any wonder that there are countless combinations that make each person's voice unique?

Dr. Voice Science explains how your voice travels

How voice travels: Recall your high school physics teacher explaining sound? For many of  us, an analogy of a stone dropped into a quiet pond was helpful. As the rock  displaces water, waves ripple from the central point. The motion gets  passed on to surrounding water, until the ripple effect dies out, or the water  reaches the shore.

In the same way, your voice displaces air surrounding your mouth,  but the major effect is a chain reaction  of sound waves. If you make a high  squeak, air around you moves up and down rapidly (short  wavelength). A low grunt makes air move up and down slowly (longer wavelength).

Remember: a short wavelength will go past you at a high rate (more frequently). A long wavelength travels slower. This is the key to sound frequency: the higher the pitch, the higher the sound wave frequency.

The same changes that affect your body as it ages -- less muscle and strength, more body fat, slower movements, and degeneration of body tissues -- impact your voice as you get older. Usually as people age their speech slows down, syllables and words are elongated, and sentences are punctuated with more pauses for air. Pitch and loudness may be reduced, and tremors can appear. All in all, an older person's speech lacks "pep."

 Scientific studies show:

• As they age, men's larynxes change more than women's, and these changes occur earlier.
• Male voice pitch tends to rise with age, while female voice pitch stays the same, or may lower slightly.
• Many elderly people have hearing loss. This may cause them to speak louder, which, in turn, can affect vocal health.

Vocal limitations:  Age will undoubtedly bring changes to your voice. Healthy living can delay some changes, but no one stays young forever. At some point --like the rest of your body  -- your voice will age.  Larynx cartilages become harder (and therefore less flexible) with age. This may reduce a person's pitch range, which is particularly significant for those who enjoy singing. The respiratory system tends to work less efficiently as we age, thus speaking will become a more difficult task.

Microscopic studies of the fibers located in vocal folds show that these structures become stiffer and thinner, producing higher pitched voice, especially in males. The bulky muscle of the vocal fold  (the thyroarytenoid)  may shrink with age, creating a weaker, breathier voice.

Control your vocal destiny: The good news is that you have some control over how quickly your voice ages. A nutritious diet, rest, exercise and a positive attitude all help to keep the body working well. Exercise strengthens muscles and increases lung capacity.  There is some evidence that an older, but healthy, person can have a stronger, better functioning voice than a younger, but less healthy, individual. Some of the ageing of the structures in the larynx aren't necessarily detrimental. Remember that effective voicing isn't dependent on brute force, but rather, a well-coordinated onset and offset of the laryngeal muscles. Some voice therapies may help to re-energize an ageing voice. For example, certain techniques can tone laryngeal muscles, while others are designed to teach how to use more forceful patterns to produce an audible voice.           

Male vs. female: The most basic genetic difference is, after all, sex. Vocally speaking, post-adolescent females usually have higher and lighter voices as compared to males. Why?

• On average, the male larynx is about 20 percent larger than that of the female. The part of the vocal fold that vibrates is more than the 20 percent size difference we might expect, though. Rather, the vibrating portion of the vocal folds is more like 60 percent longer in the male as compared to the female.
• The vocal fold edges in the male favor easy closure of the airspace between them. Because of innate differences in shape, women tend to have more air escape during song or speech, or "breathy" voices.
• Without delving into mechanical laws, male vocal anatomy allows men to produce more acoustic power. In other words, it is easier for the male vocal system to create a powerful voice.     

Defuse your vocal environment: So, you can't change your social history and you can't easily change the anatomical shape of your voice-producing structures. But, you certainly can de-stress your body.

Try a vocal stress-buster: Use yawns: Recreate that relaxed feeling you get after awakening from a refreshing nap. Open your mouth wide and yawn. Let some air escape. Your throat feels open and easy. Open your mouth wide and yawn again. Sigh a little as you release the air. Yawn again, this time making a full-blown sigh on your exhalation. This technique makes voicing feel easy, doesn't it? This is called your easy voice. A yawn-sigh technique is actually a form of voice therapy. (We've only presented a brief sample here.) Yawning helps the speaker drop the larynx, widen airspace between the vocal folds and open up the throat for relaxed voicing.