A voice disorder is an abnormality of one or more of the three characteristics of voice: pitch, intensity (loudness), and quality (resonance).
The National Institute on Deafness and Other Communication Disorders estimates that approximately 7.5 million persons in the United States suffer from some sort of voice disorder. The negative impact of a voice disorder is often social, psychological, professional, and economic (as in the case of a singer or actor).
Voice is typically described in terms of three characteristics: pitch, intensity, and quality. Pitch may be described as the relative tone of a person's voice—how high or low it is, how monotonous, or how it demonstrates repeated inappropriate pitch patterns. A disorder may result from pitch being inappropriate for an individual's age and gender. An inability to perceive pitch and pitch patterns may result in a monotonous voice, a high-pitched voice, or inappropriate use of repeated pitch patterns.
Loudness describes the volume or intensity of a person's voice. A person who spends a great deal of time in a noisy location or who is suffering from hearing loss may speak with high intensity, or louder than normal. A soft or inaudible voice may be associated with a psychological condition such as shyness or with a structural defect of the vocal cords.
Some disorders of voice quality are related to how the vocal cords function: breathiness is caused by vocal cord vibration that does not have a closed phase, while hoarseness is caused by vocal cords that are closed too tightly, so they cannot vibrate properly. Other disorders are related to how the voice resonates in the oral (mouth), nasal (nose), and pharyngeal (throat) cavities. If the nasal passage becomes blocked such as with a cold, then air is unable to reach the nasal cavity and a voice sounds hyponasal. Hypernasality results when too much air passes through the nasal cavities during phonation or when there is an obstruction in the anterior nasal cavities (pinching the nostrils).
Causes and symptoms
Normal voice production
The larynx is an organ found in the neck that helps to control the flow of air during breathing and to produce sound during speech. The vocal folds, also called the vocal cords, are two folds of muscle covered by a thin membrane that lie inside a framework of cartilage and soft tissue. The tension, position, and shape of the vocal folds are controlled by a number of muscles called intrinsic muscles.
Prior to the production of sound, the vocal folds are brought together by the intrinsic muscles. During exhalation, air pressure builds up beneath the closed vocal folds, causing them to separate. They are brought back together, only to separate again when pressure increases. This cycle repeats itself approximately 200 times per second in order to produce sound.
Abnormal voice production
Some of the most common causes of voice disorders in adults include infection, inflammation, vocal misuse or abuse, cancer, neuromuscular disorders, and psychological problems. In children, vocal misuse or abuse is the most common cause of voice disorder of quality.
INFECTION. A viral or bacterial infection may directly or indirectly result in voice problems. Upper respiratory infections may cause inflammation of the vocal fold membranes, resulting in changes in voice pitch and/or quality; this condition is called acute viral laryngitis. Recurrent respiratory papillomas (RRP) are wart-like growths caused by infection by the human papilloma virus (HPV); papillomas may grow on the larynx or in the throat, nose, or trachea and cause hoarseness and/or shortness of breath.
INFLAMMATION. A condition called laryngopharyngeal reflux disease (LPRD) has been associated with approximately 55% of voice disorder cases. LPRD is caused by the backflow (reflux) of acidic stomach contents into the larynx, causing inflammation. Hoarseness, difficulty swallowing, pain, and coughing are some symptoms of LPRD.
Exposure to cigarette smoke has been shown to cause inflammation of the larynx, leading to a negative change in voice quality. Long-term tobacco use has also been associated with the development of LPRD. Reinke's edema, a term used to describe very swollen vocal cords, is another condition common in long-term smokers; fluid accumulates under the outer covering of the vocal folds and causes the voice to become low pitched.
VOCAL MISUSE OR ABUSE. Examples of vocal misuse are singing or speaking out of range and producing harsh vocal sounds. Extended screaming and yelling are other examples of vocal abuse. The result of vocal misuse or abuse may be swelling of the vocal folds (edema), followed by the formation of vocal fold nodules (calluses). Consequences may range from vocal fatigue or hoarseness to vocal fold hemorrhage (bleeding).
LARYNGEAL CANCER. Laryngeal cancer accounts for 2-5% of cancers diagnosed in the United States. Chronic tobacco and alcohol use are major risk factors for developing laryngeal cancer. Symptoms include chronic hoarseness, coughing, sore throat, difficulty swallowing or breathing, and/or pain that radiates to the neck.
NEUROMUSCULAR DISORDERS. Vocal fold paralysis and paresis (partial paralysis) are examples of neuromuscular voice disorders. The cause of vocal fold paralysis is usually due to trauma or to cancer. It may also occur as a result of tumor involvement of the laryngeal nerves. Spasmodic dysphonia (SD) is another neuromuscular disorder and is caused by abnormal contractions of the muscles that control the vocal folds, resulting in a hoarse, shaky, and/or strained or strangled voice. Finally, the causes of neuromuscular disorders include degenerative conditions both of the nervous system and muscle.
PSYCHOLOGICAL CONDITIONS. Voice is often affected by one's emotions; psychological stress may cause changes to loudness or pitch. More rarely, voice disorders may be caused by psychological trauma or extreme stress. Aphonia, or a complete loss of voice, may be a result. Often, such voice disorders may be successfully treated with psychological therapy.
A variety of technologies are available to examine the larynx for abnormalities, including:
- Laryngoscopy: The indirect examination involves holding a small mirror at the back of the throat in order to visualize the larynx. In a direct examination, a flexible (inserted through the nose to the back of the throat) or rigid (held at the back of the mouth) tube-like instrument is used to more clearly visualize the interior of the larynx.
- Video stroboscopy: A strobe light is used in this test to help visualize the rapidly vibrating vocal folds as if they were in slow motion, potentially revealing changes in the vocal folds not readily seen using other methods.
- Electromyography (EMG): A laryngeal EMG is used to examine the electrical activity of the muscles of the larynx as they contract; this may reveal injury to nerves that are important in voice production.
- Double-probe pH monitoring: Special probes are placed in the esophagus and larynx to measure the extent of laryngopharyngeal reflux (LPR) over a 24-hour period. This test is therefore useful in diagnosing LPRD.
How a voice disorder is treated depends largely on how it was caused. Often, voice therapy with a certified speech-language pathologist can dramatically improve a person's voice. Voice therapy may include vocal and listening exercises, information on vocal hygiene (appropriate uses of voice), and education regarding proper voice technique. Treatment may also be the medical management of contributing health factors such as allergies and, in some cases, surgery. Other than medical treatment, therapy may include modification of the environment and psychological counseling.
A promising treatment for SD is injection with small amounts of a bacterial toxin called botox into the muscles of the larynx. The toxin temporarily weakens the laryngeal muscles, resulting in several months of improved voice quality.
Occasionally, surgery may be required to repair damaged vocal folds or remove cancerous tumors. Laser surgery has been used successfully in laryngeal surgery due to its precise cutting beam. Treatment of laryngeal cancer may include chemotherapy, radiation therapy, and/or partial or total laryngectomy, in which part, or all, of the larynx is removed. Voice therapy before and after surgery is recommended to provide the patient with a new mode of speech, if necessary.
Health care team roles
Common health care professionals involved with the care of a patient with a voice disorder may include:
- speech-language pathologists,
- otolaryngologist, specialists who treat disorders of the ears, nose, and throat
- respiratory therapists
- psychiatrist or psychologist
- oncologists, cancer specialists
- audiologists, hearing specialists
In order to prevent the development or deterioration of a voice disorder, patients are recommended to:
- Drink six to eight glasses of water a day and minimize intake of alcoholic and caffeinated beverages.
- Decrease exposure to cigarette smoke.
- Avoid unnecessarily coughing or clearing the throat, or speaking or singing out of range.
- Seek medical care if hoarseness or other voice changes persist for longer than 10 days.
Botox— A toxin produced by the bacteria Clostridium botulinum that can provide temporary relief to people suffering from spasmodic dysphoria.
Neuromuscular— Relating to the muscles and nerves.
Otolaryngologist— A specialist who treats disorders of the ear, nose, and throat.
Trachea— The windpipe.
American Speech-Language-Hearing Association (ASHA). 10801 Rockville Pike, Rockville, MD 20852. (888) 321-ASHA. 〈http://www.asha.org〉.
National Institute on Deafness and Other Communication Disorders (NIDCD) Information Clearinghouse. 1 Communication Avenue, Bethesda, MD 20892-3456.(800) 241-1044. 〈http://www.nidcd.nih.gov〉.
The Voice Foundation. 1721 Pine Street, Philadelphia, PA 19103. (215) 735-7999. 〈http://www.voicefoundation.org〉.
"Frequently Asked Questions Regarding Voice Problems." University of Pittsburgh Voice Center 5 July 2001. 〈http://www.upmc.edu/upmcvoice/faq.htm〉.
"Questions/Answers about Voice Problems." American Speech-Language-Hearing Association 5 July 2001. 〈http://www.asha.org/speech/disabilities/Voiceproblems.cfm〉.
"Voice and Laryngeal Disorders." The Voice Center at Eastern Virginia Medical School 3 July 2001. 〈http://www.voice-center.com/dis_index.html〉.
"What are Voice Disorders and Who Gets Them?" Center for Voice Disorders of Wake Forest University 1 November 1999. 〈http://www.wfubmc.edu/voice/voice_disorders.html〉.