Video Stroboscopy of the Vocal Cords

The Human Voice

If you touch the front of your neck while you say something, you will be able to feel your throat vibrating. This is because you have two flaps of skin inside your throat called vocal cords.

When you speak or sing, air from your lungs is forced over the vocal cords causing them to vibrate. In turn, this makes the air in your throat and mouth vibrate at the same rate. Muscles in the throat stretch the vocal cords tighter to make high sounds and relax them to make deeper tones. Women generally have higher voices than men because their vocal cords are shorter.

The basic sound from the vocal cords can be altered a great deal through movements of the mouth, tongue, and lips. In this way, we can produce all of the many variations of found in human languages.

Vocal Cords Singing

Many different parts of your body influence how you sing, but understanding how they all work together to produce the best sound is the key to great vocal cord singing. Of course it is important to know about breathing for singing and singing posture, but knowing where the vocal cords - your muscles for singing - are located and how they make tone is just as important. When developing good vocal technique, you need to understand how your breath, posture and tension affect how your vocal cords work.

Where are your vocal cords?

Your vocal cords are inside your larynx (pronounced lar-inks), which is the source of your singing voice. Your vocal cords are two small bands of tissue stretching across your larynx that vibrate to create pitch.

Click Here for The Ultimate Guide To Professional Singing

How do vocal cords create pitch?

Your vocal cords coordinate with your breath to release a pitch by opening and closing (vibrating) as your breath passes through. Each vibration of your vocal cords is called a "cycle of vibration" or "glottal cycle". If you're singing the same note that an orchestra plays to tune their instruments, your vocal cords are vibrating at 440 cycles per second - yes that's fast. So in order to make your vocal cords vibrate quickly, you need to keep your breath flowing otherwise you run out of air and can't sustain the tone.
In addition we have to make sure that our posture is correct. If we are not standing correctly, our breathing mechanism doesn't work well so we can't get the air moving for singing. Allowing ourselves to get too tense also prevents the body from working efficiently, which in turn can affect the vocal cords. Tense jaws, chests, and locked knees all make it impossible to breath and produce good tone.

Male Vocal Cords and Female Vocal Cords

Males and females have different vocal cord sizes. Adult male voices are usually lower pitched and have larger folds. The male vocal folds are between 17mm and 25mm in length. The female vocal cords are between 12.5 and 17.5 in length. The difference in vocal cord size between males and females means they have differently pitched voices. Additionally, genetics also causes variances amongst the same sex, with men's and women's voices being categorized into differentsinging voice types.
The home singing courses in the table below will provide you with all the information and vocal cord exercises you need to master your voice and sing like a star.

New UD tissue-engineering research focuses on vocal cords

UD scientists Xinqiao Jia and Randall Duncan are shown with the novel bioreactor that Jia designed. The device can simulate the demanding, high-frequency environment in which vocal cord cells live, vibrating back and forth at up to 100 hertz (100 times a second). Photo by Kathy F. Atkinson

1:54 p.m., July 31, 2007--Damaged or diseased vocal cords can forever change and even silence the voices we love, from a family member's to a famous personality's.
Julie Andrews, who starred in such classics as The Sound of Music, is among the professional singers who have undergone surgery to remove callus-like growths that can form from overuse of these two small, stretchy bands of tissue housed in the larynx, or voice box. Sadly, Andrews may never fully recover her singing voice after surgery on her vocal cords in 1997.
Engineering pliable, new vocal cord tissue to replace scarred, rigid tissue in these petite, yet powerful organs is the goal of a new University of Delaware research project. It is funded by a five-year, $1.8 million grant from the National Institutes of Health's National Institute on Deafness and Other Communication Disorders.
Xinqiao Jia, UD assistant professor of materials science and engineering, is leading the project. Jia's research focuses on developing intelligent biomaterials that closely mimic the molecular composition, mechanical responsiveness and nanoscale organization of natural extracellular matrices--the structural materials that serve as scaffolding for cells. These novel biomaterials, combined with defined biophysical cues and biological factors, are being used for functional tissue regeneration.
Randall Duncan, associate professor of biological sciences and mechanical engineering at UD and an expert in cellular biomechanics and signal transduction, is a co-investigator on the project. He will assist the interdisciplinary research team in determining how vocal cord cells respond to mechanical forces, which is the first step in engineering functional vocal cord tissue. Duncan is actively involved in Jia's career development as her senior mentor at UD.
Rodney Clifton, professor of engineering at Brown University and a member of the National Academy of Engineering, is providing the project with a unique testing capability, using a device he invented that can measure the mechanical properties, or elasticity, of tissue samples at human speech frequencies. Jia began working with Clifton a few years ago when she was a postdoctoral researcher and he was a visiting scientist at the Massachusetts Institute of Technology.
Also collaborating on the project is Dr. Robert Witt, a head and neck oncologist at Christiana Care Health System, in Newark, Del. Witt will provide clinical expertise in vocal cord pathology. The research partnership was established through the Center for Translational Cancer Research, which is directed by Mary C. Farach-Carson, professor of biological sciences and material sciences at UD.

Dr. Robert Witt, a head and neck oncologist at Christiana Care Health System, is collaborating on the UD research project. Photo courtesy of Robert Witt.

According to Jia, the vocal cords are more accurately defined as “vocal folds.” Each vocal fold is a laminated structure consisting of a pliable vibratory layer of connective tissue, known as the lamina propria, sandwiched between a membrane (epithelium) and a muscle. These flexible folds of tissue, coated in mucous to keep them moist, operate like an elevator door and must come together to produce a sound.
When you talk or sing, the folds may vibrate more than 100 times a second from the air that is forced up from the lungs through the trachea. However, excessive use or abuse of the voice can lead to scarring of the vocal fold lamina propria, which disrupts their natural pliability, resulting in hoarseness and other symptoms of vocal dysfunction.
“The reduction of vocal-fold scarring remains a significant therapeutic challenge,” Jia said.
Jia and her colleagues want to explore two parallel tissue-engineering approaches to regenerate the lamina propria. One method focuses on injecting gelatin-like materials, composed of soft, strong and long-lasting hydrogels, into damaged tissue to improve its pliability and prevent scar formation.
In the second approach, the scientists want to form functional tissue from a combination of vocal fold connective tissue cells (fibroblasts), artificial extracellular matrix, and biological cues and mechanical stimuli that capture the mechanical and biological characteristics of the natural organs.
“In order to grow a functional tissue in vitro, you need to provide the cells with a biological and physical environment that is as close to that of the natural tissue as possible,” Jia said.
To mimic the complex and rigorous movement experienced by vocal fold tissue, the researchers have constructed a bioreactor capable of delivering well-defined vibrational and tensile stresses.
The device, which Jia designed, simulates the demanding, high-frequency environment in which vocal fold cells live, vibrating back and forth at up to 100 hertz (100 times a second). Not only do the vocal folds collide as they open and close, driven by air from the lungs, they also must be able to elongate as the pitch of the voice changes, a movement that occurs at a much slower frequency of 1-2 hertz (1-2 times a second), according to Jia.

Image of normal vocal cords, courtesy of the Milton J. Dance Jr. Head and Neck Center at the Greater Baltimore Medical Center, Baltimore. For video of the vocal cords in action and vocal cord disorders,click here.

“The combination of vocal fold fibroblasts, elastic and bioactive artificial extracellular matrices, and a dynamic bioreactor offers an exciting opportunity for in vitro tissue engineering of vocal fold lamina propria,” Jia noted.
Earlier this year, Jia received the National Science Foundation's Faculty Early Career Development Award. The highly competitive award is bestowed on those scientists deemed most likely to become the academic leaders of the 21st century.
Jia received her bachelor's degree in applied chemistry and master's degree in polymer chemistry and physics from Fudan University in Shanghai, China, and a doctoral degree in polymer science and engineering from the University of Massachusetts at Amherst.
Before joining the UD faculty in 2005, Jia worked as a postdoctoral researcher with Robert Langer, a pioneer in tissue engineering at the Massachusetts Institute of Technology. Langer recently was awarded the National Medal of Science, the nation's highest honor for science and technology.
Article by Tracey Bryant