Phonological disorder occurs when a child does not develop the ability to produce some or all sounds necessary for speech that are normally used at his or her age.
Phonological disorder is sometimes referred to as articulation disorder, developmental articulation disorder, or speech sound production disorder. If there is no known cause, it is sometimes called "developmental phonological disorder." If the cause is known to be of neurological origin, the names "dysarthria" or "dyspraxia" are often used. Phonological disorder is characterized by a child's inability to create speech at a level expected of his or her age group because of an inability to form the necessary sounds.
There are many different levels of severity of phonological disorder. These range from speech that is completely incomprehensible, even to a child's immediate family members, to speech that can be understood by everyone but in which some sounds are slightly mispronounced. Treatment for phonological disorder is important not only for the child's development to be able to form speech sounds, but for other reasons, as well. Children who have problems creating speech sounds may have academic problems in subject areas such as spelling or reading. Also, children who sound different than their peers may find themselves frustrated and ridiculed, and may become less willing to participate in play or classroom activities.
Phonological disorder is often divided into three categories, based on the cause of the disorder. One cause is structural problems, or abnormalities in the areas necessary for speech sound production, such as the tongue or the roof of the mouth. These abnormalities make it difficult for children to produce certain sounds, and in some cases make it impossible for a child to produce the sounds at all. The structural problem causing the phonological disorder generally needs to be treated before the child goes into language therapy. This therapy is especially useful, because, in many of these cases, correction of the structural problem results in correction of the speech sound problem.
The second category of phonological disorder is problems caused by neurological problems or abnormalities. This category includes problems with the muscles of the mouth that do not allow the child sufficient fine motor control over the muscles to produce all speech sounds. The third category of phonological disorder is phonological disorder of an unknown cause. This is sometimes called "developmental phonological disorder." Although the cause is not known, there is much speculation. Possible causes include slight brain abnormalities, causes rooted in the child's environment, and immature development of the neurological system. As of 2002, there is research pointing to all of these factors, but no definitive cause has been found.
The symptoms of phonological disorder differ significantly depending on the age of the child. It is often difficult to detect this disorder, as the child with phonological disorder develops speech sounds more slowly than his or her peers; generally, however, he or she develops them in the same sequence. Therefore, speech that may be normal for a four-year-old child may be a sign of phonological disorder in a six-year-old.
Nearly all children develop speech sounds in the same sequence. The consonant sounds are grouped into three main groups of eight sounds each: the early eight, the middle eight, and the late eight. The early eight include consonant sounds such as "m," "b,", and "p." The middle eight include sounds such as "t," "g", and "chi," and the late eight include more complicated sounds such as "sh," "th," "z," and "zh." Many children do not normally finish mastering the late eight until they are seven or eight years old. As children normally develop speech sound skills, there are some very common mistakes that are made. These include the omission of sounds, (i.e., frequently at the end of words), the distortion of sounds, or the substitution of one sound for another. Often the substitution is of a sound that the child can more easily produce for one that he or she cannot.
The diagnosis for phonologic disorder depends greatly on the age of the child in question. Children who are four years old may have speech production difficulties that show normal development for their age, while children who are eight years old and making the same mistakes may have phonological disorder. In children with phonological disorder, the pattern and order of speech sound acquisition is usually similar to that of normally developing children. However, the speech sound skills develop more slowly, so age is an important factor in determining a diagnosis of phonological disorder. Children with phonological disorder may make the same speech sound mistakes as younger, normally developing children. In some cases, however, children with phonological disorder have demonstrated more instances of omissions, substitutions, and distortions in their speech.
When exploring a diagnosis of phonological disorder, it is generally recommended that a physician check for other possible causes of the signs and symptoms. A child's hearing should be checked, because speech sounds that are not heard well by a child cannot be imitated and learned well. In school-age children, reading comprehension should be checked to discover any other language disorders, which are sometimes present in addition to phonological disorder. Any general developmental delays should also be checked by the physician. It is important to remember that for some children whose native language is one other than English, the problems with speech sounds may result from poor crossover of sounds between the child's languages. Therefore, when diagnosing a child with a different native language, it is recommended that tests involve the child's first language, as well as English. Also, it must be remembered that in some parts of the country, normal pronunciation of some words is different from pronunciation in other parts of the country. Therefore a child's background and history can be very important in making a diagnosis.
The Diagnostic and Statistical Manual of Mental Disorders ( DSM-IV-TR ) states that for a diagnosis of phonological disorder to be made, three general criteria must be met. The first criterion is that the child is not developing speech sounds skills considered to be appropriate for his or her age group. Also, this lack of speech sound acquisition must be causing problems for the child at home, at school, or in other important aspects of the child's life. If the child is mentally retarded, has problems with his or her speech muscles or hearing, or if there is environmental deprivation, a diagnosis of phonological disorder may still be appropriate. The diagnosis can only be made, however, if the lack of speech sounds skill is considered greater than the child's other problems.
Phonological disorder of unknown cause is considered significantly more common than phonological disorder that is caused by neurological or structural abnormalities. It has been estimated that 7–8% children who are five years old have phonological disorder with any cause (developmental phonological disorder). About 7.5% of children between the ages of three and eleven are thought to have development phonological disorder. Phonological disorder is more common in boys than it is in girls. Estimates suggest that two to four times as many boys as girls have the disorder. Children who have phonological disorder are more likely to have other language problems and disorders. Children with one or more family members who have this or similar language disorders are also considered to be more likely to have phonological disorders.
Treatment by a speech-language pathologist is generally recommended for children with phonological disorders. The therapy will differ depending on an individual child's needs, but generally takes the form of practicing sounds. Sometimes the child is shown the physical ways that the sound is made, such as where to place the tongue and how to form the lips. Repetition of the difficult sounds with the therapist is an integral part of treatment. There is debate, however, over the way that children with more severe forms of the disorder should be treated. Some therapists believe that the sounds that are learned later in development should be addressed first, even if the child has not developed the more simple sound skills. Other therapists believe that simple sounds should be treated first, as it is easier for children with phonological disorder to master them. One other school of thought is that when the child develops a sense of accomplishment when these sounds are mastered, and he or she will more willingly continue with treatment. There is ongoing research on this debate, and the results as of 2002 are still mixed.
Children who have phonological disorder because of neurological or structural problems that do not allow them to produce some sounds are often helped to find approximate alternatives for the sounds within the range of sounds that they are able to produce.
The prognosis for children with phonological disorder is generally good. For many children, the problem resolves spontaneously. It is reported that in 75% of children with mild-or-moderate forms of the disorder, and whose problems do not stem from a medical condition, the symptoms resolve before age six. In many other cases, children who receive treatment eventually develop normal or close to normal speech. In some cases, there may be mild effects that last until adulthood, but speech is completely understandable. For children with phonological disorder due to a neurological or structural cause, the outcome generally rests on how well the cause of the problem is treated.
There is no known way to prevent phonological disorder. A healthy diet during pregnancy and regular prenatal care may help to prevent some of the neurological or structural problems that can result in the disorder.
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Weismer, Susan Ellis, and others. "Nonword Repetition Performance in School-age Children with and without Language Impairment." Journal of Speech, Language, and Hearing Research 43, no. 4 (August 2000).
American Academy of Child and Adolescent Psychiatry. 3615 Wisconsin Ave. NW, Washington, DC 20016-3007. (202) 966-7300. <www.aacap.org> .
The American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007-1098. (847) 434-4000 <www.aap.org> .
American Speech-Language-Hearing Association. 10801 Rockville Pike, Rockville, MD 20852. (800) 638-8355. <http://www.asha.org> .
Tish Davidson, A.M.