Voice Disorders

Voice Production

Voice is produced by the cyclical vibrations of the vocal folds within the larynx. The vocal folds at rest are apart to allow breathing. During speech production, they approximate, relax, and repeat to produce a vibration pattern. This pattern is measured in cycles per second and represents an individual's fundamental frequency, or the frequency band of their speaking voice. Males typically have a fundamental frequency around 150 cycles per second, and females around 250 cycles per second.

The fundamental frequency changes when a person has, or acquires, a voice disorder. Voice disorders are categorized by various voice qualities associated with difficulties in voice production at the level of the larynx. There is either a problem with the vocal folds being able to sufficiently approximate or relax during the vibration cycle. Both aspects of the cycle are critical to appropriate voice production, function, and quality.

Etiology

There are several categories of voice disorders, each representing a type of dysfunction of the vocal mechanism. The main categories are breathy, harsh, and hoarse.

A breathy voice is the by-product of an air leakage during the approximation phase of the vibratory cycle. This leakage causes noise and a weak sounding voice. There are many things that could prevent complete vocal fold approximation, such as vocal nodules, edema, vocal fold paralysis, physical asymmetry, infection, or contact ulcers. In some cases, the dysfunction may originate from the neural level, subsequently causing laryngeal dysfunction, as in the case of stroke and other brain lesions.

A harsh voice is similar in physiology to a breathy voice but the periodicity of vocal fold vibration is much lower. One or both vocal folds are not able to vibrate at their optimal speed, creating a noisy low-pitched voice. Vibration is also aperiodic, creating random acoustic patterns in the voice. Some common causes attributing to harsh voice are smoking, alcohol use, and vocal abuse such as yelling. Yelling causes increased friction between the vocal folds and can lead to vocal pathologies such as vocal nodules, contact ulcers, and polyps.

A hoarse voice is one that presents elements of both the breathy and harsh voices. A hoarse voice has a periodicity that is so low that you can often hear each separate vibration cycle. People who have a hoarse voice often avoid speaking altogether because of associated pain, vocal fold damage, and social judgment. Acute laryngitis is a common cause of a hoarse voice, where the vocal folds are swollen, thick, heavy, and unable to vibrate efficiently. Chronic exposure to smoke, pollution, and other carcinogens can produce lesions on the vocal folds, which may render them paralyzed.

Treatment

Individuals experiencing a degradation in voice quality should see an otolaryngologist for a physical evaluation. Often, a hoarse voice is a symptom of a more serious pathology, such as laryngeal cancer. In this case, a laryngectomy may be necessary, and normal speech production permanently lost. Assistive speech devices and alternative speech strategies are options for laryngectomy patients, but can be upsetting to communication partners and affect both communication and social interactions.

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