Speech sound disorders
are speech disorders
in which some speech sounds (called phonemes
) in a child's (or, sometimes, an adult's) native language are either not produced, not produced correctly, or are not used correctly.
Errors produced by children with speech sound disorders are typically classified into four categories:
- Omissions: Certain sounds are not produced -- entire syllables or classes of sounds may be deleted; e.g., fi' for fish or 'at for cat.
- Additions (or Commissions): an extra sound or sounds are added to the intended word.
- Distortions: Sounds are changed slightly so that the intended sound may be recognized but sound "wrong," or may not sound like any sound in the language. The best known example of a distortion is the lisp.
- Substitutions: One or more sounds are substituted for another; e.g., wabbit for rabbit or tow for cow.
Note that sometimes, even for experts, telling exactly which type has been made is not obvious -- some distorted forms of /r/ may be mistaken for /w/ by a casual observer, yet may not actually be either sound but somewhere in between. Further, children with severe speech sound disorders may be difficult to understand, making it hard to tell what word was actually intended and thus what is actually wrong with it.
There are three different levels of classification when determining the magnitude and type of an error that is produced:
- Sounds the patient can produce
- A: Phonemic- can be produced easily; used meaningfully and contrastively
- B: Phonetic- produced only upon request; not used consistently, meaningfully, or contrastively; not used in connected speech
- Stimulable sounds
- A: Easily stimulable
- B: Stimulable after demonstration and probing (i.e. with a tongue depressor)
- Cannot produce the sound
- A: Cannot be produced voluntarily
- B: No production ever observed
Note, that omissions do not mean the sound cannot be produced, and some sounds may be produced for easily of frequently when apearing with certain other sounds: someone might be able to say "s" and "t" separately, but not "st," or may be able to produce a sound at the beginning of a word but not at the end. The magnitude of the problem will often vary between different sounds from the same speaker.
Speech sound disorders may be subdivided into two primary types, articulation disorders (also called phonetic disorders) and phonemic disorders (also called phonological disorders). However, some may have a mixed disorder in which both articulation and phonological problems exist. Though speech sound disorders are associated with childhood, some residual errors may persist into adulthood.
Articulation disorders (also called phonetic disorders, or simply "artic disorders" for short) are based on difficulty learning to physically produce the intended phonemes. Articulation disorders have to do with the main articulators which are the lips, teeth, alveolar ridge, hard palate, velum, glottis, and the tongue. If the disorder has anything to do with any of these articulators, then it's an articulation disorder. There are usually fewer errors than with a phonemic disorder, and distortions are more likely (though any omissions, additions, and substitutions may also be present). They are often treated by teaching the child how to physically produce the sound and having them practice its production until it (hopefully) becomes natural. Articulation disorders should not be confused with motor speech disorders, such as Dysarthria
(in which there is actual paralysis of the speech musculature) or Childhood Apraxia of Speech
(in which motor planning is severely impaired).
In a phonemic disorder (also called a phonological disorders) the child is having trouble learning the sound system of the language, failing to recognize which sounds contrasts contrast meaning. For example, the sounds /k/ and /t/ may not be recognized as having different meanings, so "call" and "tall" might be treated as homophones
, both being pronounced as "tall." This is called phoneme collapse
, and in some cases many sounds may all be represented by one -- e.g., /d/ might replace /t/, /k/, and /g/. As a result, the number of error sounds is often (though not always) greater than with articulation disorders and substitutions are usually the most common error. Phonemic disorders are often treated using minimal pairs
(two words that differ by only one sound) to draw the child's attention to the difference and its effect on communication.
Some children with phonemic disorders may seem to be able to hear phoneme distinctions in the speech of others but not their own. This is called the fis phenomenon based on scenario in which a speech pathologist will say, "Did you say 'fis,' don't you mean 'fish'?" To which the child responds, "No, I didn't say 'fis,' I said 'fis'."
Though phonemic disorders are often considered language disorders in that it is the language system that is effected, they are also speech sound disorders in that the errors relate to use of phonemes. This makes them different from Specific Language Impairment (SLI), which is primarily a disorder of the syntax (grammar) and usage of language rather than the sound system. However, the two can coexist, affecting the same person.
Other disorders can deal with a variety of different ways to pronounce consonants. Some examples are glides and liquids. Glides occur when the articulatory posture changes gradually from consonant to vowel. Liquids can include /l/ and /.1/ (-Alex Restrepo).
Mixed Speech Sound Disorders
In some cases phonetic and phonemic errors may coexist in the same person. In such case the primary focus is usually on the phonological component but articulation therapy may be needed as part of the process, since teaching a child how to use a sound is not practical if the child doesn't know how to produce it.
Even though most speech sound disorders can be successfully treated in childhood, and a few may even out grow them on their own, errors may sometimes persist into adulthood. Such persisting errors are referred to as "residual errors" and may remain for life.
Most speech sound disorders occur without a known cause. A child may not learn how to produce sounds correctly or may not learn the rules of speech sounds on his or her own. These children may have a problem with speech development, which does not always mean that they will simply outgrow it by themselves. Many children do develop speech sounds over time but those who do not often need the services of an SLP to learn correct speech sounds.
Some speech sound errors can result from physical problems, such as.
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