Hearing loss does not affect a person's intellectual capacity or ability to learn. But a child who sustains hearing loss early in life may lack the language stimulation and speech development experienced by children who can hear. The reason is, hearing loss stunts imitation of essential speech patterns and sounds, and prevents the individual from monitoring his or her errors. The academic progress of a child with hearing loss often lags behind that of children who can hear. It is common for hearing-impaired adolescents to be four or more grades behind their peers. But early language stimulation through sign language and speech therapy can help considerably. Speech therapists identify, evaluate and treat deficiencies of voice, articulation, language, and rate and rhythm. Therapists who work with the hearing impaired frequently team with other professionals, including a neurologist, an ear, nose and throat specialist, a psychologist and or a social worker. Therapy may be given individually or in a group setting. The treatment method depends on the client's age, case history and type of speech disorder.