In most of these columns we speak of the larynx as an instrument, the instrument of voice. But what does the larynx do when it is not singing? Even the most dedicated Wagnerian marathoner doesn’t sing all the time, and in fact the larynx spends most of its time busy with other work. In order to understand this structure more, it might be interesting to examine the larynx from a non-singing perspective.
Hundreds of thousands of years before the first “Una voce poco fa” was uttered, the larynx was already fully employed in a mundane but essential fashion, as a sphincter. This remains its main purpose. It sits on top of the trachea, and protects the lower airway. It closes rapidly, completely and reflexively hundreds of times a day. This occurs as part of the shunting mechanism that allows the pharynx, the common pathway, to alternate as a channel for the passage of air and of food. When we swallow, the larynx rises, tips forward, and closes. The closure involves three different valves, of which the lowest, and most important, are the vocal folds. People unable to close their vocal folds, such as may be seen in cases of paralysis, either aspirate their food and drink, or at least begin to do so, before the cough reflex expels the swallowed material from the trachea.
The cough reflex also involves the larynx. The vocal folds are pressed together, air pressure is built up in the trachea, and then the folds suddenly open and air rushes past. This rush of air according to some authorities reaches speeds of 90 miles per hour, and carries with it mucus, debris and any other foreign material from the lungs, bronchi and trachea. Without forceful closure of the folds, the cough is merely a noisy and much less effective throat clearing. The vocal folds vibrate during cough, and it is interesting to speculate whether the first voice began as a kind of cough?
The larynx also controls the stiffness of the chest. The thoracic cage is normally in constant motion, as air fills and empties out of the lungs. As we breathe, the ribs swivel up and down, and the muscles of respiration relax and contract. Since the thoracic cage also serves as an anchor point for the muscles of the upper limbs, it needs at times to be rigid. For the arms and upper body to work most efficiently, the insertion of the muscles involved must be held steady. This is done by trapping air in the lungs and stiffening the thorax, a maneuver which requires the vocal folds to be pressed tightly together. Lifting weights, doing push-ups or other types of high-effort exercise usually involve this tight closure of the vocal folds, called the Valsalva maneuver. A recent Japanese paper (published in the journal The Laryngoscope) demonstrated that even with less than maximal exertion, some people squeeze the larynx in this fashion. It is for this reason that singers should consider other forms of exercise, and they should be conscious of exhaling during exertion, such as is involved with exercise machines.
Even the biggest of couch potatoes can not avoid the Valsalva maneuver, since this mechanism is also involved in moving the bowels, giving birth and other physiologic activities. The splinted rib cage allows the abdominal muscles to contract more effectively. Forceful contraction of the abdominal muscles, in addition to squeezing the vocal folds together, may have another deleterious consequence in those with acid reflux due to hiatal hernia: The increased intra-abdominal pressure can push stomach acid up into the esophagus, and even to the pharynx.
In truth, the larynx is never still. Even during quiet breathing, the vocal folds gently swing in and out. In more forceful breathing, the movements become more marked although never harmful. It is only when the folds actually touch that their surfaces can rub against each other and a voice is produced. This is seen in athletes during high exertion — remember those grunting tennis players at Wimbledon? — and in patients with lungs stiff from emphysema who need to increase the air pressure in the lungs to properly ventilate the smaller airways.
So what does the larynx do when it is not singing? A great deal! I hope with this brief overview your respect and wonder at this humble sphincter of muscle, membrane and cartilage increases even more.
DISCLAIMER: The suggestions given by Dr. Jahn in these columns are for general information only, and not to be construed as specific medical advice, or advocating specific treatment, which should be obtained only following a visit and consultation with your own physician.
