Three parts of speech
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.
Dr. Voice Science explains voice qualities
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.
How age changes your voice
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.
Nature versus nurture of 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.
Lots of lovely layers
What is a vocal fold: muscle, soft tissue, fluid? All of them! Like skin, vocal folds have layers — five, to be exact. Each layer contains a specific make-up and purpose, and by working together they enable you to speak. There is no other structure in the body quite like the human vocal fold.
Its outermost layer, the epithelium, is a thin skin that acts as a barrier and vibrates easily.
Just inside the epithelium is the lamina propria -- three layers of non-muscular tissues. The outer and middle layers contain stretchy fibers (elastin) that allow your cords to stretch; the innermost layer of the lamina propria has fibers that keep it from stretching too much out of shape.
Finally, the largest and bulky part of the vocal fold is a muscle that can shorten or lengthen, thicken or thin, and stiffen or relax. It makes up about three-quarters of the vocal fold.
Each layer contributes a necessary and unique component to voicing.
Sticky, squishy vocal folds
The multi-layered vocal folds make it a fascinating subject for research. Because each layer's composition is distinctly different from that of its neighbor, its behavior also varies. Two areas of particular interest to scientists are the "sticky" and "squishy" factors. Investigators would more likely label these viscosity and elasticity. Both characteristics impact how easily the vocal folds can settle into vibration. If vocal folds are overly sticky or don't deform well when brought together, voicing is effortful. Scientists believe vocal fold cells repair work heavily impacts tissue behaviors. For example, if cell repair work is significant -- due to rigorous voice use -- viscosity and elasticity are affected.
Thus, traditional wisdom is correct. After a heavy voice-use day, teachers should try to then vocally "take it easy" during cell repair.
Hot topics in voice research
Voice recognition: Synthesized speech was first produced mid-century. Since then, we have gone from merely emitting speech sounds to dictation programs that can handle continuous speech, recognize recurring word patterns, get smarter with use, and save the user countless hours. The simplest programs respond to a specific user's voice and vocabulary. More complex programs are voice-independent and match vowels and consonants in speech groups to words in a dictionary. Because of varied accents and dialects, no perfect program has yet emerged. It also makes us wonder: as the burden for a task such as word processing is shifted from the hands to the voice, will our vocal systems hold up?
Voice simulation: Voice simulation models use scientific laws to mimic the way the body produces voice. Scientists start with images of the head and neck (MRI's) as the system produces vowel and consonant sounds. Customized software connects these still shapes to imitate the human while speaking. Powerful computers integrate (mathematically) how airflow (breath), vibration of the vocal folds (phonation), and behaviors of the vocal tract and articulators contribute to voice. When perfected, the simulated voice model can aid in the study of voice and speech disorders, singing and even speech training and rehabilitation. For example, the voice surgeon can "test" the influences of his plan for surgery on the computer model before s/he takes the scalpel in hand.
Tissue engineering: Scientists are attempting to bioengineer human voice structures outside the body. They collect human vocal cells, and carefully grow them under special laboratory conditions. The process is not unlike a gardener carefully nurturing a seed into a healthy plant. The cells multiply and are subjected to vibrations by a device to mimic the vibrations of the vocal folds. While growing a complete vocal fold in the lab is far from reality, initial steps to artificially engineer simple vocal cells are encouraging. At some point in the future, patients whose vocal folds have been injured by cancer, severe trauma or chemical exposure can be given new, fresh vocal tissue.