What is a Speech Impairment?
When a person is unable to produce speech sounds correctly or fluently, or has problems with his or her voice, then he or she has a speech disorder. Difficulties pronouncing sounds, or articulation disorders, and stuttering are examples of speech disorders.
When a person has trouble understanding others (receptive language), or sharing thoughts, ideas, and feelings completely (expressive language), then he or she has a language disorder. A stroke can result in aphasia, or a language disorder.
Both children and adults can have speech and language disorders. They can occur as a result of a medical problem or have no known cause.
(Retrived from American Speech-Language-Hearing Association)