Audiologic evaluation, particularly the behavioral aspect, is
an interactive process. The clinician and the individual being tested must interact communicatively with each other to obtain accurate hearing thresholds. This interaction requires a minimal level of intellectual functioning and adaptive abilities for an individual to respond appropriately to speech and acoustic stimuli. Chromosomal abnormalities, heredity, pre- and perinatal infections, intrauterine growth retardation, and inappropriate or indiscriminate exposure of
the fetus to drugs during pregnancy are common causes of mental retardation. Socioeconomic factors such as poor nutrition, maternal neglect, and poverty can compound preexisting low intellectual function. Although there is some disagreement concerning the
use of the term mental retardation, there is unanimity that an individual with this condition must exhibit low intellectual functioning, an impairment due to physical insult, disease, or an abnormality before age 18, and an impairment in adaptive abilities (Batshaw and Shapiro, 1997). IQ scores, age of onset, and adaptive impairments (although still controversial) have often been used to de¢ne mental retardation. According to the American Psychiatric Association (1994), a person with mental retardation should exhibit the following characteristics: an IQ score of 70 or less on an individually administered IQ test, concurrent de¢cits in adaptive functioning, and onset before the age of 18 years. Impairment in adaptive ability is demonstrated by the person’s inability to perform at least two culturally expected and age-appropriate skills required for everyday living such as communication, self-care, social/interpersonal skills, functional academic skills, home living, safe use of community resources, and self-direction in work, leisure activities, and health. Some of the everyday living skills that are vital during audiologic evaluation and rehabilitation are easily compromised by more severe mental retardation.
For instance, a person with mild mental retardation (IQ score of approximately 70) would perform much better on speech measures that require repeating words or sentences than an individual with severe retardation (IQ score of approximately 35
