Speech disorders, also known as speech impediments, are instances where a person's normal speech is disrupted. Two of the most common speech disorders are stuttering and lisping. In certain cases, extreme speech disorder can render a person mute, or unable to speak.
Speech pathologists will use three levels of classification in determining the type and severity of a speech disorder. This classification leads to proper treatment of the disorder. The levels of classification are:
- Sounds the individual can produce, including phonemic (produced easily) and phonetic (produced upon request);
- Stimulable sounds, either easily produced or after demonstration;
- The realization that a person cannot produce a sound, either voluntarily or ever observed.
Causes of Speech Disorders
While the causes of speech disorders are often unknown, there are several major types of speech disorder. Apraxia is the inconsistent pronunciation and rearranging of sounds. Dysarthria is a paralysis of the speech muscles. Both of these may be caused by strokes.
Dysprosody is the rarest of speech disorders, and usually results from something like a brain tumor or injury. It is marked by alterations in speech intensity, rhythm, cadence and intonation. Stuttering is perhaps the most common speech disorder, affecting upwards of one percent of the adult population.