Why do many children with CAPD (central auditory processing disorder) have difficulty learning vowels, and what can be done to treat this problem?
To address this question fully would require more space than I have available. However, let me mention a few ideas. There are many reasons that children with APD may have difficulty learning vowels. These can include teaching method, how well the child is prepared to learn, and the child's basic reading skill level. In this commentary, I will address only issues that are audiologically related to this relatively common problem.
In order to “learn” vowels, a child must have the ability to identify and discriminate vowels auditorally. These processes are highly dependent on the proper function of the entire auditory system. Therefore, the clinician needs to evaluate the patient's entire auditory system—peripheral and central—before suggesting a management approach.
DETERMINING VOWEL-DISCRIMINATION SKILLS
It is critical to find out if the child has sufficient auditory discrimination skills to distinguish one vowel from another. Some vowels are easy to identify and discriminate, but others, such as the short (e) and short (i), are indeed difficult—especially for a child whose auditory system is functioning below par. In such cases, measures of frequency discrimination may be in order. For if the child's auditory system lacks normal frequency discrimination, the child may be unable to discriminate and identify vowels that are similar acoustically. Therefore, one should determine a difference limen (a just-noticeable difference) for children who are struggling with learning vowels.
Here, however, a problem confronts the clinician. Curious as it may seem, the overwhelming majority of clinical audiologists never evaluate auditory discrimination. Remember, the NU#6 and W-22 lists do not assess speech discrimination; they assess speech recognition. In general, audiologists do not have tests of auditory discrimination.
There are reasons for this, including that auditory discrimination has been primarily a research domain of the psychoacoustician. Although much has been learned about basic auditory discrimination, little of it has carried over to the clinic. Some clinics (including ours) attempt to evaluate auditory discrimination, even though there really are no tests clinically available. Audiology needs a clinically feasible procedure that can measure frequency, intensity, and duration discrimination in children and adults.
Clinically, we do have some informal procedures for evaluating vowel discrimination, but we often go by what school learning specialists/teachers tell us in regard to vowel identification and discrimination abilities for a particular child.
Where vowel identification and discrimination are clearly a problem, several management approaches are available, including these:
* We have discussed our vowel training approach previously.1,2 This procedure focuses essentially on individual vowel identification and discrimination. We feel it is critical that children be able to perceive vowels correctly on an individual basis. Vowels are placed in triads or pairs and the child is asked to identify and/or discriminate them in a variety of ways. An adaptive auditory training approach is employed. An error matrix is used to keep track of types of errors so that more time can be spent on the vowel combinations that are the most challenging to the student.If progress is not made on certain vowels, we may move to discrimination of tone pairs for frequency, intensity, and duration. If drilling on identification and discrimination of vowels in isolation results in progress, we will then place the vowels in CVs and then words.Another procedure that can be used with CVC words is to parcel the vowels and consonants into two acoustic channels. This allows the vowel to be independent of the consonants. The vowel then can be routed to one channel and presented at a higher level than the consonants in the other channel, thus permitting the vowel to be heard better. Practice on vowels should be done in a quiet room so there is no masking of low-frequency acoustic cues. The practice should be consistent and progressive.
* The Earobics program is a commercially available program that provides a significant amount of vowel training.3 This program is touted to improve reading and phonemic awareness. One way it does this is by enhancing vowel identification and discrimination. It is highly animated and children enjoy the tasks.
* Sloan's book provides considerable materials for auditory training.4 It also includes a number of vowel-discrimination tasks using a wide variety of vowel combinations.
1. Musiek F: Habilitation and management of auditory processing disorders: Overview of selected procedures. JAAA
2. Musiek F, Baran J, Schochat E: Selected management approaches to central auditory processing disorders. Scand Audiol
4. Sloan C: Treating Auditory Processing Difficulties in Children
. San Diego: College-Hill Press, 1986.