Breathing for singing I

Your Voice: An Inside View by Scott McCoy, DMA

The respiratory system—or pulmonary system—is the power source and actuator of the vocal instrument. In this capacity, the lungs serve a function similar to the bellows of a pipe organ or the air bladder of bagpipes; in essence, they function as a storage depot for air.

This is not, of course, the primary biological function of the respiratory system, which must perpetually oxygenate the blood and cleanse it of excess carbon dioxide to maintain life.   Respiratory Anatomy The respiratory system is housed within the axial skeleton. This portion of the human skeleton consists of the spine and thorax (ribcage). The remainder of the skeleton, including the skull, pelvis, arms and legs is called the appendicular skeleton. Posture is largely a function of the relative positions and balance between these skeletal regions. As such, the appendicular skeleton will become more important later in this Chapter when breathing methods are discussed.

Spine
Discussion of the respiratory framework must begin with the spine itself, which consists of twenty-four individual segments called vertebrae. Stacked together to form a gentle “S” curve in the anterior/posterior plane, the vertebrae gradually become narrower and thinner from the bottom to the top of the spinal column. The bottom five are called the lumbar vertebrae. These are the largest and thickest bones in the spine and are responsible for carrying most of the weight of the upper body. Curvature in this region acts as a shock absorber, helping to prevent injury during heavy lifting. Thoracic vertebrae make up the next twelve segments of the spine. These bones are somewhat smaller than the lumbar vertebrae and possess flat areas called facets for the attachment and articulation of the ribs.

The seven cervical vertebrae complete the top of the spine. The topmost cervical vertebra is called the atlas and is specially shaped to fit snugly into the base of the skull and carry the weight of the head. The second cervical vertebra, called the axis, features a projection from its anterior segment called the dens or odontoid process that inserts into the atlas. Together, these two vertebrae provide a pivot around which the skull can be tilted and rotated.

All of the vertebrae—except the atlas—have a small projection from their posterior called a spinous process that serves as an attachment point for muscles of the back. In the lumbar region, these projections are robust and somewhat stubby, extending at nearly a right angle to the spine. In the thoracic region, the spinous processes are longer and extend obliquely away from the spine. The spinous process of the sev- enth cervical vertebrae is particularly large and can be easily seen or felt in most people, especially while bending over. This provides a landmark for the division be- tween the cervical and thoracic regions and can be useful in establishing correct posture. Two transverse processes also extend laterally from each vertebra.

At the base of the spine, five sacral vertebrae are found, which are fused together to form the sacrum. An additional five, very small vertebrae, which are also fused together, extend beyond the sacrum to form the coccyx or tailbone. The sacrum joins with a group of bones called the ilium, pubis and ischium to create the pelvis, a very strong structure that serves as the attachment points for the lower extremities and as a girdle for the contents of the abdomen.

Knowledge of the structure, shape and attachments of the spine has significant pedagogical consequences. It must be remembered that the spine has a natural, s- shaped curve. While this curve should not be exaggerated, as seen in severe cases of lordosis (swayback), it should also not be artificially removed and straightened. At least one prominent text on singing technique instructs that correct posture can be established by lean- ing against a wall with the knees bent and the feet placed several inches forward. The singer then presses the small of his back into the wall, making it as straight as possible. Finally, he is to stand up while maintaining the same vertebral posture—and sing (McKinney, 1994). While this technique might be somewhat beneficial for the correction of lordosis, the impact on normal bodies is contrived and unnatural. When the entire skeleton is considered, another significant pedagogical implication becomes clear. The central pivot-point for bending forward and back is not at the waist but at the joint between the pelvis and the hips. Many singers and teachers use breathing exercises that include bending over to increase awareness of abdominal motion during respiration. If the instruction or intent is to bend from the waist, this exercise compresses the abdominal area and may actually inhibit free breathing. If, however, the singer bends forward from the hips, the spine and abdomen are lengthened and released, making the exercise much more effective.

Thorax (ribcage)
The thorax or ribcage houses the lungs and heart. It consists of twelve pairs of ribs (in spite of what is implied in Genesis, men and women have the same number of ribs), which are attached to the thoracic vertebrae through flexible joints that permit movement up and down. Limited movement is also possible in the anterior/posterior plane.

The highest four pairs of ribs attach individually to the breastbone or sternum through the flexible connection of the costal cartilage. Ribs five through ten share a common cartilaginous connection to the sternum. The bottom two ribs are free- floating, with no connection to the sternum. The sternum itself consists of two bony plates called the manubrium and the corpus (body). At the base of the corpus, a small projection called the xiphoid process is found, to which some of the abdominal muscles attach. The flexible connections of the ribs to the spine and sternum allow for a significant range of motion. Through contraction of respiratory muscles, the entire thorax can be raised and depressed, and made larger or smaller in diameter. All of these changes in dimension result in either inhalation or exhalation.

Lungs
Why do dimensional changes of the thorax result in breathing? The answer lies in an old axiom you might remember from your school days: nature abhors a vacuum. The lungs, which lie within the thorax, are organs, not muscles, and therefore do not have the ability to move of their own accord. However, they still must be enlarged for inhalation and made smaller for exhalation. This can occur because the lungs are cou- pled to the interior wall of the thorax by ac- tion of the pleurae, or pleural sac.

The pleurae is a serous (water permeable) membrane that causes the thorax and lungs to adhere to each other much in the same way a wet plastic bag will adhere to a window. Because of the pleurae, dimensional changes in the thorax are directly trans- ferred to the lungs; if it gets bigger or smaller, the lungs do the same.

To better understand how a vacuum is created in the lungs, we must take a brief foray into the realm of physics. Robert Boyle, a 17th-century British scientist, discovered that when a gas, such as air, is contained in a soft-walled enclosure, its pressure and volume will be inversely proportional (if one goes up, the other goes down). This is easily visualized through a balloon. If a balloon is squeezed, its volume becomes smaller and the pressure of the air within it increases; conversely, if the bal- loon could be made larger without the addition of extra air, the pressure within it would decrease.

To inhale, the volume capacity of the thorax and lungs must be increased. This, according to Boyle’s Law, results in a decrease in air pressure. In fact, the air pressure in the expanded lungs is now actually lower than atmospheric pressure—a vacuum has been created. Air rushes in to fill this vacuum and create equilibrium between the pressures inside and outside the lungs. Exhalation reverses this process. The thorax and lungs are made smaller, decreasing their volume and thereby increasing air pressure. Air in the lungs now rushes out to equalize lung and atmospheric pres- sures. Because of Boyle’s Law, anytime the volume capacity of the thorax and lungs is increased, inhalation occurs; anytime it is decreased, exhalation occurs. It is extremely important to remember the cause-and-effect relationship of expansion and contraction during breathing. Expansion of the chest and/or abdomen upon inhalation is not the result of air rushing in to fill the lungs; rather, muscles are contracted to expand thoracic capacity, resulting in a partial vacuum and inhalation.

The lungs themselves are made of porous, spongy material. The right lung is composed of three separate sections, called lobes; the left lung must compete for space with the heart and is therefore slightly smaller, having but two lobes. Air comes into the lungs through the trachea (windpipe), which divides into two separate bronchial tubes. These further divide into the lobar bronchi, which insert into the separate lobes of each lung. Once inside the lungs, the bronchi divide into smaller and smaller segments, eventually arriving at the alveoli or alveolar sacs, which is where the ac- tual exchange of blood gasses occurs. The alveoli are highly compressible and are responsible for much of the elasticity of lung tissue. Healthy, mature lungs contain vast numbers of individual alveoli with enough surface area to cover a tennis court! Different sources cite widely varying numbers of total alveoli. According to Zemlin, there are about seven million (Zemlin, 1998); Raymond Kent, however, places the number closer three hundred million, a number also cited by J. Anthony Seikel, et al (Kent, 1997; Seikel, 2000).

How much air do the lungs actually hold? Physiologists employ several different measurements of lung capacity. Total lung capacity (TLC), the maximum amount of air the lungs can contain, typically ranges between four and seven liters, varying ac- cording to body size, gender and age. Not all of this air, however, is accessible dur- ing respiration. Vital capacity (VC) measures the amount of air that can actually be expelled following a maximal inhalation, averaging three to five liters. Vital capacity represents the “capital” with which a singer must work. Those three to five liters must be carefully meted out to extend over the longest phrase and to control the entire range of musical expression. The difference between the total lung capacity and the vital capacity is the residual volume (RV). Varying over a range of one to two liters, residual volume represents the quantity of air that normally cannot be expelled from the lungs, regardless of the expiratory force applied by the various breathing muscles (the lungs never fully deflate in a living person unless they lose their pleural connec- tion and collapse due to injury). The quantity of air that is moved during breathing is called tidal volume. Under exertion—and particularly during singing—this may ap- proach 100% of vital capacity. At rest, however, tidal volume is likely to be only about a half-liter (Baldwin, 1948; Hoit, 1987).

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