There are two separate elements governing volume in singing: what happens at the vocal fold level and what happens in the resonating system of the vocal tract after the sound waves travel upward.
Factors at the vocal fold level affecting loudness include subglottal air pressure, glottal resistance and amplitude of vocal fold displacement from the midline during each vibratory cycle.
Glottal resistance is increased with greater closed quotient. As closed quotient increases, subglottal air pressure increases. Closed quotient is increased when the intrinsic muscles of the larynx (the thyroarytenoids (TA), lateral cricoarytenoids (LCA), and interarytenoids (IA)) contract more strongly. This ability can be developed through vocal training.
As the vocal folds vibrate open and closed they convert aerodynamic energy into acoustic energy containing a source sound that includes the fundamental or pitch and many partials.
The longer the vocal folds remain closed in this...
Changing pitch involves changing the rate at which the glottal wave repeats as a result of the ever-shifting changes in the length and tension of the vocal folds.
Contraction of the body of the vocal fold correlates with lower pitch. When the thyroarytenoid (TA) muscle contracts, it pulls the back or posterior portion of the folds closer to the front or anterior portion, bunching the folds up.
When the thyroarytenoid (TA) muscle is contracted it is more tense; however, the mucosa overlying the vocal folds becomes floppier, so the mucosa vibrates more slowly. The shorter, thicker fold structure combined with the slower vibration of the mucosa results in a lower pitch.
In the upper register, when we sing higher pitches, the vocal folds vibrate faster as they become longer, thinner, and tauter. This happens when the cricothyroid (CT) muscle contracts, tilting the thyroid cartilage down and forward on the cricothyroid ligament, causing it to move away from the arytenoid...
Lower and upper register vocal fold phonation can be contrasted regarding the:
Also known as the modal register, the lower register is characterized by the following:
What is a Register?
Everyone has experienced the difference, in their own voice, between singing high pitches and singing low pitches. Most people have also experienced the challenge of voice breaks or cracks.
How are registers determined? What is a register, exactly?
A register in the human voice is a particular series of tones, produced in the same manner (by the same vibratory pattern of the vocal folds), and having the same basic quality.
The American College Dictionary
Definitions of Registers by prominent pedagogues:
Registers originate in laryngeal function. They occur because the vocal folds are capable of producing several different vibratory patterns. Each of these vibratory patterns appears within a particular range of pitches and produces certain characteristic sounds. From these statements, it can be deduced that each register has three constituted elements: a certain vibratory pattern of the vocal folds, a certain series of pitches,...
Inadequate vocal fold closure produces a breathy voice due to excessive airflow through the glottis. Breathy singing could be an indication of various issues such as a lack of vocal development, inefficient onset, vocal fold swelling (edema), aberrations including cysts such as nodules or polyps, poor vocal training, and the stylistic use of a flip to falsetto.
Breathy singing is typical of an Undeveloped category singer throughout their range, an Unbalanced-Pulled Lower singer in the upper register before training, and the low notes of the Unbalanced-Light Lower singer.
To counteract inadequate fold closure, in the first five steps of the Eight Steps of Vocal Development we use adducted onset exercises to encourage better vocal fold closure. These exercises are also known as coup-de-glotte; they are a temporary tool. We discard the use of the coup-de-glotte in Step Six and beyond.
Other ways to counteract breathy singing include voiced-stop consonants...
When we sing, the vocal folds must be brought together to the midline of the glottis to initiate phonation. This is known as approximation or adduction.
It works like this: the vocal folds are adducted or drawn together from the posterior (back) end of the larynx due to the approximation and rotation of the arytenoid cartilages as the lateral cricoarytenoid (LCA) and interarytenoid (IA) muscles contract.
The gliding and swiveling/rotating action of the arytenoid cartilages brings the attached vocal folds toward one another at the midline, allowing the inner edges of the folds to meet and leaving a slit along the middle for air to travel through.
After they are brought to midline, the folds begin to vibrate open and closed in response to air flowing up through the trachea from below the glottis (subglottally).
When we swallow, the folds remain closed so that food is more effectively directed toward the esophagus or food tube.
When we inhale, the folds are open.
When we phonate (make...
Tension in the vocal folds occurs through both a lengthwise stretching known as longitudinal tension and by adductive tension that draws the folds toward one another at the posterior (back) end of the larynx.
Longitudinal tension of the vocal folds is achieved through contraction of the cricothyroid (CT) muscles that stretch and lengthen the folds by tilting the thyroid cartilage forward, bringing the thyroid and cricoid cartilages closer together.
Adductive tension is a result of the contraction of the interarytenoid (IA) muscles and the lateral cricoarytenoid (LCA) muscles as the arytenoid cartilages rotate and move toward one another, closing the posterior gap in the glottis and creating vocal fold resistance to subglottal air pressure. This is medial compression.
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Closing the Gap: The Intrinsic Muscles
The vocal folds are open or abducted for inhalation. When we take a deep breath, the vocal folds are fully abducted. When we speak or sing, the folds should adduct or come together at the onset of phonation; they subsequently vibrate open and closed during phonation.
The glottis or space between the vocal folds is closed by the intrinsic muscles. All the intrinsic muscles other than the transverse interarytenoid are paired muscles- there are two of each. The intrinsic muscles are:
The intrinsic muscles are those within and around the larynx. The intrinsic muscles that contribute to vocal production include:
1. The TA or thyroarytenoid muscles comprise the main body of the vocal fold. They contract to shorten and thicken the vocal folds and are predominantly active in the lower register or chest voice.
The terms TA and vocalis are often used interchangeably, though they are different muscle bundles. The vocalis is the medial (inside) portion of the fold body (the part closest to the ligament) and is comprised of slow-twitch muscle fibers. The thyroarytenoid (TA) portion is comprised of fast-twitch muscle fibers.
The thyroarytenoid (TA) muscle adducts, shortens, and thickens the vocal folds, rounding their edges as the body of the folds contracts. When TA activity shortens the folds, the first two outer layers of the fold (the epithelium and superficial lamina propria (mucosa) and the intermediate and deep lamina propria (ligament) become slacker. The...
To innervate is to supply or stimulate. In the human body, nerves originate in the brain and branch out to the spinal cord, connecting to the muscles of the body. Signals from the nerves activate and control our muscles, and also give us feedback. This two-way process is called innervation.
Two nerves innervate the larynx: the recurrent laryngeal nerve and the superior laryngeal nerve, both branching out of the vagus nerve. The recurrent laryngeal nerve wraps around the aorta, the main artery leading out of the heart, and then comes back up and attaches to the larynx.
Men have larger vocal folds and a correspondingly larger and more prominent larynx than women and children do. The length of the vocal folds is about 16 mm or .62 inch for an adult male and about 10 mm or .39 inch for an adult female.
The male larynx is more prominent due to the 90-degree angle of formation; the female larynx has a softer 120-degree angle and is...