Auditory discrimination test

Definition

An auditory discrimination test is a screening or diagnostic assessment tool designed to identify and diagnose deficits in auditory discrimination.>

Purpose

Auditory discrimination is a central auditory processing skill that involves the ability to differentiate among phonemes—the smallest significant units of sound in a language. Phonemes are combined into words. For example the word "goes" is made up of three phonemes: "g," "oh," and "zzz." Auditory discrimination is part of phonology which, in turn, is one of the five components of language.

Auditory discrimination tests (ADTs) are one type of auditory analysis tests, which are used to measure how well a child understands speech and the spoken word. ADTs are designed to measure a child's phonological awareness—the ability to focus on and manipulate phonemes within spoken words. Phonological awareness skills include the ability to do the following:

• compare and contrast speech sounds
• separate and blend phonemes
• identify phonemes within spoken words
• combine phonemes into spoken words

ADTs measure a child's ability to detect subtle similarities and differences between speech sounds. Two of the most commonly used ADTs are Wepman's Auditory Discrimination Test (WADT) and the Goldman-Fristoe-Woodcock Test of Auditory Discrimination.

Auditory discrimination skills are very important in the classroom. Activities that require auditory discrimination skills include the following:

• following directions
• reading
• writing
• spelling

Auditory discrimination ability or phonological awareness skills have long been correlated with reading ability. Some specialists believe that ADTs should be a component of all reading programs and that poor auditory discrimination can be a major factor in children's failure to reach reading targets. The WADT is used to evaluate communication skills in general, as well to identify potential reading difficulties and to predict certain types of speech defects. Because it requires a child to recognize small differences between phonemes, the WADT is widely used to measure a child's readiness for reading instruction using a phonic method.

Some underachieving but gifted children have learning disabilities that are caused by deficits in central auditory skills, including auditory discrimination. The WADT commonly is used to test for an auditory discrimination deficit in such children. Deficits in auditory discrimination are also believed to be one of the causes of central auditory processing disorder (CAPD). There are various methods for addressing auditory discrimination problems in children.

Description

Auditory discrimination is one component of central auditory processing skills or auditory perception. The other components are as follows:

• auditory memory: the ability to recall a sequence of auditory stimuli or phonemes
• auditory blending: the ability to perceive separate phenomes, divide a word into phenomes, and combine phenomes into words
• auditory comprehension: the ability to comprehend and interpret information that is presented orally

The WADT

The WADT, first published in 1958 and revised in 1973, is designed to measure the ability of children aged four to eight to recognize small differences between English phonemes. The test consists of 40 pairs of words. The words in a pair are of equal length. In ten of the pairs the words are identical. In the remaining 30 pairs the words differ by a single phoneme. The test requires the child to differentiate between the following:

• 13 word-pairs differing in their initial consonant, such as "coast" and "toast"
• four word-pairs differing in their medial vowels, such as "pat" and "pet"
• 13 word-pairs differing their final consonant, such as "lease" and "leash"
• 10 identical word-pairs or false choices, such as "jam" and "jam"

Often the WADT is administered by a special education teacher or a speech/language pathologist. The test is administered orally to an individual child who is seated such that neither the examiner's mouth nor the words on the test form are visible to the child. The examiner reads each word-pair only once, and the child indicates whether the word-pair consists of different or identical words. The test requires about five to 10 minutes to administer. The performance rating scale ranges from "very good development" for the child's age to "below adequate" for the child's age. Two equivalent forms of the test are provided so that children can be retested if their initial scores are questionable or if the test is needed for evaluating the effectiveness of subsequent remedial instruction. The WADT is widely considered to be both reliable and valid, with norms based on the scores of 2,000 children.

The WADT is considered to be a fast, inexpensive means of screening children for auditory discrimination deficits and for identifying children who are slower than average in developing auditory discrimination skills. It also is used to identify children who may have difficulty learning the phonics that are necessary for learning to read. The WADT often is used as a component of formal reading assessments.

Other ADTs

Other ADTs include the following tests:

• Goldman-Fristoe-Woodcock (G-F-W) Test of Auditory Discrimination, which includes visual stimuli
• Goldman-Fristoe-Woodcock (G-F-W) Diagnostic Auditory Discrimination Test
• auditory word discrimination subtest of the Test of Auditory Perceptual Skills (TAPS); the subtest uses only auditory stimuli
• Auditory Discrimination and Attention Test
• Schonell Auditory Discrimination Test which, like the WADT, is a component of some formal reading assessments

In one type of ADT the test administrator says a word and the child is asked to repeat the word, leaving out a syllable or sound. For example the examiner says "outdoor" and tells the child to say the word but to not say "out." The correct answer is "door." Children's responses are graded according to the following:

• The child gives the correct answer quickly.
• The child takes more than five seconds to give the correct answer.
• The child answers incorrectly.

The child's auditory discrimination skill is assigned a grade level:

• a kindergartner told to repeat the word "cucumber" without the "cu (q)" should easily answer "cumber"
• a first-grader told to repeat "please" without the "zzz" sound should easily answer "plea"
• a second-grader told to repeat "clay" without the "k" should easily answer "lay"
• a third-grader told to repeat "smock" without the "mmm" sound should be able to easily answer "sock"

The Sheshore Measures of Musical Talent is a widely used standardized test for measuring musical abilities in students applying to music programs, conservatories, and colleges and universities. It tests the listener's auditory discrimination abilities with regard to the following:

• pitch
• volume
• rhythm
• sound duration
• tonal quality or timbre
• tonal memory

Electrophysiological tests

Sometimes electrophysiological techniques are used to assess various types of central auditory processing including auditory discrimination. These techniques measure auditory evoked potentials (AEPs), which are changes in the brain's neural-electrical activity in response to the reception of auditory signals. AEPs are recorded via electrodes on the child's scalp. During auditory discrimination decisions, which involve various processes including attention and recognition, a large positive peak called P300 appears at about 200 milliseconds after the presentation of the word or other auditory stimulus. The electrical signals that contribute to P300 come from various parts of the brain. The most common way of measuring auditory discrimination with P300 is the oddball paradigm, in which a series of low-frequency auditory stimuli is randomly interspersed with high-frequency stimuli. The child attempts to count the number of high-frequency pitches. Significant differences in the appearance of the P300 peak have been found between poorly achieving gifted children and highly achieving gifted children.

Precautions

ADTs can give confusing or false negative results. Many children do well on the auditory word discrimination subtest of TAPS, which uses auditory stimuli, but perform poorly on the G-F-W Test of Auditory Discrimination, which uses visual stimuli. Such children may have good auditory discrimination skills but poor auditory-visual integration discrimination.

Risks

In the early 2000s research suggests that auditory discrimination and other perceptual processes may not be primary factors in predicting reading ability and learning disabilities. Thus some children may be falsely labeled with a learning disability because of their results on ADTs. Other children might fail to be identified as candidates for early intervention for reading or other learning difficulties on the basis of their ADT scores.

Normal results

ADTs are standardized by testing large numbers of children to determine the normal range of scores for children of a given age. The vast majority of children have ADT scores within the normal range. Children who score significantly below the normal range may be referred for additional assessment. Early intervention for children with low ADT scores may include exercises and activities designed to improve auditory discrimination.

KEY TERMS

Auditory discrimination —The ability to detect small similarities and differences between sounds.

Auditory evoked potential (AEP) —A change in the neural-electrical activity in the brain in response to auditory signals.

Auditory perception —The ability to comprehend and interpret auditory signals.

Central auditory processing skills —The skills needed for auditory perception, including auditory discrimination, auditory memory, auditory blending, and auditory comprehension.

Phonemes —The basic units of sound in a language.

Phonological awareness —The ability to hear and manipulate the sounds that make up words.

Phonology —The science of speech sounds and sound patterns.

Wepman 's Auditory Discrimination Test (WADT) —A commonly used test for evaluating auditory discrimination skills.

Parental concerns

ADTs are short, simple tests that do not require preparation on the part of the child. However parents should be aware of the normal developmental milestones of speech and language development . Although no two children reach these milestones at precisely the same age, a significant lag may indicate the need for assessment of auditory discrimination and/or other components central auditory processing. Typical milestones include:

• producing vowel sounds within the first six months of life
• understanding certain words by six to 12 months of age
• speaking first words at 12–18 months
• combining words by 18–24 months of age
• understandable speech and the use of consonant sounds by two to three years
• speaking faster and with longer and more varied sentences by three to four years
• a vocabulary of more than 1,500 words, sentences averaging five words, and the ability to modify speech by four to five years of age

Resources

ORGANIZATIONS

American Speech-Language-Hearing Association. 10801 Rockville Pike, Rockville, MD 20852. Web site: <http://asha.org>.

International Listening Association. Web site: <www.listen.org>.

WEB SITES

Burk, Rickie W. "Interview with Dorothy Kelly." MSHA News. Mississippi Speech-Language-Hearing Association. <www.mshausa.org/kelly.html> (accessed November 9, 2004).

Troost, B. Todd, and Melissa A. Walker. "Diagnostic Principals in Neuro-otology: The Auditory System." Available online at <www.bgsm.edu/neurology/Rosenberg/audio1.html> (accessed November 9, 2004).

Margaret Alic, PhD