How We Produce and Perceive Sound
Tuning the human voice is not as simple as tuning a piano or guitar. On those instruments, the tension of each string is adjusted to vibrate at the correct frequency for the desired pitch. To understand pitch and tuning, it helps to know a bit about how sound is transmitted and how our ears perceive it.
Without getting too technical, sound is a wave–a back-and-forth movement of air pressure with three properties: wavelength, frequency, and amplitude. Wavelength and frequency determine the pitch, and are inversely related to one another. Amplitude determines the volume (loudness) of the sound.
A pitch we perceive as high has a shorter wavelength and greater frequency than one we perceive as low. When a sound wave strikes the tympanum (ear drum), the vibration causes tiny hair cells in the cochlea (inner ear) to generate a nerve signal that is interpreted by the brain as sound.
All musical instruments have a mechanism to generate sound and a resonating chamber to amplify it. In the human voice, the mechanism is air flow across the vocal folds and the resonating chamber consists of the nose, mouth, and throat (collectively called the pharynx and subdivided into the nasopharynx, oropharynx, and laryngopharynx).
How Our Voice Works
Our voices produce sound as air from the lungs flows across our vocal chords (which are actually vocal folds). We control the pitch of our sound in two ways:
1) by the placement of the tone in our resonating chamber.
2) by the tension of the folds as air passes over them, controlled by tiny muscles in the throat
The human voice has three qualities of sound: pitch, volume, and timbre. Pitch measures how high or low the sound is, and is determined by the larynx; volume indicates how loud or soft it is, determined by the lungs and breath muscles; and timbre refers to the resonance of the sound, determined by the placement of the tone in the resonating cavities.
Below is a diagram of the anatomy of the human vocal tract. You can refer back to it later when you’re learning how to make it work.
The larynx itself is behind the thyroid cartilage at the top of the trachea (windpipe). When we breathe, the epiglottis opens, allowing air to pass through. When we eat and swallow food, the epiglottis closes over the top of the larynx to prevent food from “going down the wrong pipe”.
Vertical cross-section of larynx viewed from left side
When we speak or sing, the vocal folds of the larynx open (abduct), close (adduct), and vibrate. The pitch of the sound (how high or low it is) is determined by how tightly the folds are closed and how fast they vibrate. When they’re tightly closed, they vibrate faster and produce a higher pitch. For lower pitches, they are open wider and vibrate slower.
interior of larynx top view of larynx
How We Breathe
The diaphragm acts as a bellows, and the chest cavity functions as a sealed vacuum chamber. As the diaphragm contracts and relaxes, it alternately draws air into the lungs and then pushes it out. The lungs are like balloons, and they are alternately inflated (when we inhale) and deflated (when we exhale).
Oxygen from the inhaled air enters the bloodstream and is carried to the rest of the body through a complex biochemical process. The sound of our voice is produced when exhaled air passes across our vocal folds and causes them to vibrate.
relaxed diaphragm diaphragm contracts downward, lungs fill with air,
trunk expands circumferentially
The volume (loudness or softness) of the sound is determined by the quantity and force of the air flow from the lungs, and is controlled by the breathing muscles: diaphragm, abdominal obliques, intercostals, and spinal muscles. Proper breath support is vital to effective projection (singing without electronic amplification).
The primary muscle involved in breathing is the diaphragm, which forms the floor of the rib cage and divides the chest cavity from the abdomen. Other related muscles are the intercostals (located between the ribs, forming the walls of the chest cavity), the abdominal obliques, and some of the spinal muscles.
To feel movement of your diaphragm, sit upright or stand tall and lay one hand lightly on the center of your abdomen with your thumb resting on your lowest rib. Watching yourself in a full-length mirror, take a deep breath. Your abdomen should expand and push your hand outward. When you exhale, your abdomen should contract.
To feel the obliques and spinal muscles, place one hand with the thumb beside your spine at the small of your back and the fingers pointing forward. Put your other hand on your side with the thumb resting on the lowest rib and the fingers pointing forward to feel the intercostals and obliques.
Take in another deep breath with both of your hands pushed outward. You should feel expansion around your entire midsection. Your chest and shoulders should not rise or move much at all.
Controlling Tone Quality
The timbre of the voice describes its tone quality, and is a function of the resonating cavities of the vocal tract: chest, oropharynx (throat), nasopharynx or mask (nose and mouth), and head/sinuses. Some singers refer to “head” and “chest” voice. Generally, the lower the pitch, the lower it resonates in the vocal tract.
A trained singer learns to produce tones that resonate in the various cavities. A large part of vocal training consists of making smooth transitions from one resonating cavity to another as you sing different pitches, and choosing where each note should resonate to produce the desired sound.
The voice is often described as having three regions or registers: upper (head voice in women, falsetto in men), middle (mask), and lower (chest voice, which is actually a misnomer—the tone range actually resonates in the laryngopharynx or throat). The transition between the registers is called the passaggio.
Each individual singer has a unique passaggio, though it usually occurs between the B flat below middle C and the E above middle C. Sopranos and tenors may have a second passaggio one octave higher. Without training, the passaggio may sound rough and feel awkward.
If you notice that your voice often “breaks” and the tone quality changes on certain pitches, or you have difficulty blending with other singers, you have likely found your passaggio. The key is to realize that the registers are not actually separate mechanisms, just different levels on a continuous scale.
Proper posture promotes efficient breathing, which is essential to projection, tone quality, and vocal range. Overall good health and physical fitness are also important.
The ideal posture for singing is erect yet relaxed. Stand with your feet directly below your hips, one foot slightly forward and your weight centered over your thighs. Your chest should be high and your shoulders back, though not too rigidly. Arms should be relaxed at your sides.
Maintaining And Caring For Your Voice
When a guitar gets hard to tune, you replace the strings. When a piano gets out of tune, you call in a tuner. Along those same lines, when your voice gets out of tune, you need to take care of your instrument.
Whether you dream of having a professional career in music or are a purely recreational singer, you want your voice to sound as good as it can and to last a lifetime. The best approach is to stay physically fit through a healthy diet, adequate sleep, and moderate exercise. It also means refraining from smoking, illegal drugs, and excessive alcohol consumption.
There is a stereotype of constant partying in the music industry, but that isn’t sustainable. Most successful recording artists have taken good care of themselves and avoided the excesses that prematurely ended the careers of such great talents as Janis Joplin, Jim Morrison, and Elvis Presley.
Try to eat a healthy, balanced diet that includes plenty of lean protein, whole grains, fruits, and vegetables, with only moderate amounts of fat and starchy, sugary foods.
Learn as much as you can about food and nutrition from reliable sources. Here are several good articles and web sites:
Harvard School of Public Health, (2008). Healthy Eating Pyramid, http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/pyramid/
Mayo Clinic Staff, (2008). “Food Pyramid: An Option For Better Eating”, http://www.mayoclinic.com/health/healthy-diet/NU00190/rss=1
U.S. Department of Agriculture, (2005) “Inside The Food Pyramid” http://www.mypyramid.gov/tips_resources/tentips.html
Drink lots of water. A hydrated larynx functions better. A rule of thumb is to drink eight glasses of water each day, but it doesn’t have to be plain water. Any non-alcoholic, non-caffeinated beverage will do: fruit juices, decaffeinated soda, coffee, tea, or flavored mineral waters all provide hydrating benefits.
Although alcohol and caffeine aren’t forbidden, they have a diuretic effect, which is the opposite of hydration.
Exercise helps keep your body healthy and your vocal apparatus strong. Strive for a minimum of 20 to 30 minutes of physical activity at least four days per week.
Even if you don’t have the budget for a gym membership, you can always walk, run, or ride a bicycle around your neighborhood. All you need is a good pair of shoes, comfortable clothes, or a bike helmet. In inclement weather, you can walk in a shopping mall.
If you are traveling, find out if your hotel has a workout facility; if not, you can simply take a walk. If the weather is bad or you’re in an unfamiliar city, you can walk in the hotel hallways. Unless you’re toting equipment, use stairs instead of elevators.
For many musicians, a full night’s sleep can be hard to come by. You’re most likely performing late at night, and it takes a while to unwind afterward. Then you may have to get up in the morning for classes or a day job. But it’s important that you try to get as much rest as possible, as sleep deprivation can be dangerous.
Without adequate sleep, you’re more likely to get in a car accident, experience a work-related injury, or make mistakes when performing any activity that requires attention to detail. in fact, studies have shown that sleep-deprived drivers are just as dangerous as drunk ones. Sleep deprivation also lowers your resistance to illness.
Try to take short naps whenever you can during the day. If you use public transportation, try to catch some shuteye on the bus or train. On weekends, sleep in if you can. It’s not actually possible to catch up on missed sleep, but the extra rest will be good for you.
If you’re eating a healthy diet and getting enough sleep and exercise, you are already giving your immune system a boost. During cold and flu season, you can reduce your chance of catching a cold or virus with these two common-sense tips:
- Wash your hands frequently. If you aren’t near a facility with running water (such as an outdoor performance venue), carry a small bottle of hand sanitizer with you.
- Try to avoid shaking hands with anyone who is coughing or sniffling. The most common method of transmission for infections is hand-to-hand contact. If you can’t avoid the handshake, wash your hands as soon as possible, and don’t touch your eyes, nose, or mouth in the meantime.
Avoid Vocal Strain
If you frequently overstrain your voice, it’s likely that either your vocal technique needs work or you need to develop a better warm-up and practice routine. If you are hoarse after rehearsals, talk with your voice teacher—and if you don’t have a voice teacher, find one! A professional can listen to you sing, identify the problem, and help you prevent future vocal strain.
Pamper yourself occasionally with an activity you enjoy. Soak in a hot tub, get a professional massage, treat yourself to a favorite dessert, or re-read a favorite book. Any small indulgence will do; it doesn’t have to be expensive.
As a vocal athlete, you need to regard your body with the same respect and attention as a professional or Olympic competitor.