Hoarsness

How does the larynx produce sound?

Inorder to understand why ones voice may be altered or "hoarse", it is necessary to understand how a normal voice is created by the voice box (larynx). Below you can see an example of a normal larynx.

The larynx is also the opening to the windpipe (trachea), which leads to the lungs. The true vocal folds, which are part of the larynx, are pearly white, and the surrounding structures are light pink. The vocal cords come apart when one breathes in to allow air to enter the lungs (picture on the left) and come together (picture on the right) when one creates a sound.

Inorder to create the sound the lungs push air out through the narrow gap between the vocal cords, this in turn causes vibration of the lining of the vocal cords. It is this which creates the sound.

To have normal voice therefore it is necessary to have:
1. Adequate flow of air through the vocal cords
2. The vocal cords on each side must come together, and move in a uniform manner.
3. The lining of the vocal cords needs to be healthy, moist and free to vibrate.

Disruption of any of the above may give rise to an altered voice.

Below are some examples of various conditions that may give rise to an altered voice.

Examples of conditions affecting the lining of the larynx. (Note that this is not a comprehensive list of laryngeal disorders, but some of the commoner ones)

Nodules are calluses on the vocal folds that occur with improper voice use or overuse. They prevent the vocal folds from meeting in the midline resulting in a raspy, breathy voice. Mostly these will respond to appropriate speech therapy. Occasionally (20% of the time), these may persist after intensive speech therapy and will require meticulous microlaryngeal surgery.

Polyps are benign lesions of the larynx that are usually located on the edge of the vocal folds and prevent the vocal folds from meeting in the midline. Polyps can interfere with voice production and may produce a hoarse, breathy voice that tires easily. These may respond to conservative medical therapy and intensive speech therapy. If the lesion fails to respond, meticulous microsurgery may be indicated.

Vocal fold hemorrhage is a very rare occurrence that usually is caused by aggressive or improper use of vocal folds (e.g. singing aloud). It is a result of rupture of a blood vessel on the true vocal fold, with bleeding into the tissues of the fold. It usually resolves itself.

Laryngeal Cancer may present as a lump on the vocal folds. This disrupts the lining, as well as preventing the vocal folds from coming together. It will thus give rise to a hoarse voice. Laryngeal cancer when detected early can be treated with either radiation or surgery, with a cure rate approaching 96%.

Laryngopharygeal Reflux may cause inflammation of the lining of the vocal folds and give rise to a hoarse voice, as well as other symptoms. It is usually easily treated medically. See the page on reflux for more information.

Incompetent Larynx
Impaired Vocal Fold Mobility, a condition where one or both of the vocal folds do not move appropriately, can be due to paralysis, paresis, scarring, or inflammation of the joints moving the vocal folds.
Vocal fold paralysis or paresis results from a lesion affecting the nerves or muscles of the larynx. Not uncommonly, following thorough investigation, no obvious cause may be found.

Laryngeal Dystonia (Spasmodic Dysphonia)
Laryngeal dystonia, or spasmodic dysphonia (SD) is a voice disorder caused by involuntary movements of one or more muscles of the larynx. There are two major types of spasmodic dysphonia: adductor and abductor, although most are a mixture of both types.

Adductor SD, with spasms causing sporadic vocal fold closures, are identified by a strained, strangled voice.

Abductor SD, with spasms causing sporadic vocal fold closures, produces a voice with interruptions of air.

Functional Disorders

Muscle tension disorder is the commonest functional disorder of the larynx. Excessive laryngeal muscle tension squeezes the vocal folds and surrounding muscles into a “fist” configuration, preventing air from moving through the vocal folds to enable normal vibration. The voice is reduced to a “squeaky” sound.

Some of the material (including the photographs) have been reproduced by kind permission of Dr C R Stansey of Texas Voice Centre.
http://www.texasvoicecenter.com/