Sound substitution is the persistent use of one normative sound instead of another. At the same time, the sound-substitute is phonetically correct (not distorted), similar in articulation or acoustic properties to the replaced sound. This violation is detected by a speech therapist during the examination of sound pronunciation and phonemic hearing. If necessary, otological diagnostics is carried out. Corrective work is aimed at the formation of articulatory praxis, the development of speech hearing, analytical and synthetic activity, and the differentiation of mixed sounds.
Substitution (substitution) and mixing (mutual substitutions) of speech sounds are phonemic (sensory, phonological) defects, usually due to incompleteness or impaired development of phonemic hearing. Substitutions are classified into the same groups as distortions of sounds, only the prefix "para-" is added to the name of the latter:
1. Parasigmatisms (from the Greek letters "sigma") - replacements of whistling and hissing:
2. Paralambdacisms (from the letter of the Greek alphabet "lambda") - replacing the sound [L] ("paw") with [U] ("uapa"), [V] ("vapa"), [Y] ("yapa") , [L ′] (“blooper”), [P] (“brine”), [S] (“yapa”), [D] (“dapa”).
3. Pararotacisms (from the Greek letter “ro”) - replacing the sound [R] (“hand”) with [R ′] (“ryuk”), [L] and [L ′] (“bow”, “hatch”) , [Y] ("yuka"), [G] ("guka"), [D] ("duka"), [V] (wooka").
4. Paraiotacisms (from the Greek “iota”) - replacing the sound [Y] with [L ′] (“shirt” - “fry”).
5. Substitutions of posterior sounds (from the Greek letters “kappa”, “gamma”, “chi”): paracapacisms - [K] to [T] (“Kolya” - “Tolya”), paragammacisms - [G] to [D ] (“head” - “dolova”), parachytisms - [X] on [T] (“tail” - “tvost”).
Also in practical speech therapy, sound substitutions include voicing defects (replacing voiced phonemes with paired deaf ones - “bite” instead of “geese”) and softening defects (replacing soft consonants with their hard pairs - “tota” instead of “aunt”). Close to the replacement and mixing of sounds, i.e. mutual interchangeability, confusion of phonemes.
Various types of sound replacement are most numerous during the age-related imperfection of sound pronunciation - the so-called physiological dyslalia. Substitutions are found in the speech development of all younger preschoolers, they are associated with the physiological immaturity of the articulatory apparatus and speech hearing.
The period of mastering sound in ontogenesis takes from 1-1.5 months and longer. It proceeds in several stages. At first, children use substitute sounds in speech. Then, having “groped” for the correct articulation and correlating the new sound with the acoustic pattern, the child begins to pronounce it in parallel with the old substitute sound. At the next stage, the new sound gradually replaces the substitute, after a while completely replacing it.
With physiological dyslalia, the following types of substitutions are more common:
Physiological imperfections of speech, and with them the sound substitutions in normal speech ontogenesis, disappear on their own by the age of 4.5-5 years.
The phenomenon of substitution is typical for the articulatory-phonemic and acoustic-phonemic forms of dyslalia. In the first case, the substitutions are due to the lack of formation of sound structures, the use of phonemes that are simpler in articulation in speech. In the second, speech hearing turns out to be undeveloped, as a result of which sounds are recognized incorrectly.
With functional dyslalia, usually hissing is replaced by whistling; sonors [R], [L], affricates [C], [H] - each other; posterior palate - explosive anterior lingual; hard ones - their soft pairs. Such defects are not prone to self-disappearance and require logopedic assistance to correct the FFN.
Dysarthria is characterized by defects in softening, voicing, mixing sounds, undifferentiated articulation. Substitutions of sounds in large numbers are found in pseudobulbar, bulbar, cortical, erased dysarthria.
Palatalization of consonants is associated with increased spasticity of the middle part of the back and the tip of the tongue. Defects in voicing are explained by a violation of the voice, its insufficient strength. The consequence of articulatory dyspraxia is the specific substitution of consonants: [G] to [D], [K] to [T], [L′] to [Y], the use of simpler sounds instead of affricates - [Ts-S′], [Ch‒ T′], etc.
For the open form of rhinolalia, phonetic defects in sound pronunciation are more characteristic, but in some cases there are also sound substitutions. So instead of explosive consonants [B], [P], fricatives [B], [F] are used; instead of the vibrant [R], the vowel [S] is pronounced with a strong exhalation, the whistling [C] is replaced by [F].
Specific are the substitutions and mixing of whistling and hissing, simplification of affricates, the use of nasal consonants [M], [N] instead of [B] and [P]. With a closed rhinolalia, on the contrary, nasal sounds are replaced by oral ones.
Violation of differentiated perception of speech with sensory alalia leads to the same undifferentiated pronunciation of sounds and words. For this form of speech disorder, unstable replacements of sounds are typical, i.e., with each pronunciation by the child, different substitutes are used. Sound replacements are numerous and varied, combined with the distortion of the syllabic structure of the word.
The substitutions of sounds and letters that occur during aphasia are called literal paraphasia. Such defects occur in acoustic-gnostic, afferent motor aphasia, when the phoneme-articuleme-grapheme-lexeme connection breaks down.
With the sensory form of aphasia, the patient's acoustic gnosis is disturbed, speech sounds cease to differ by ear. This leads to the replacement of phonemically close sounds (more often voiced by their deaf pairs and vice versa). With afferent motor aphasia, kinesthetic praxis suffers, fine articulatory movements break up. This mechanism entails the replacement of sounds similar in articulation: [M] to [B], [L] to [N].
Some types of abnormal bite can contribute to the formation of sound substitutions. In children with defects in the closure of the dentition, dentitional parasigmatism is often found. Prognathia is characterized by the replacement of [C] with [F]. Progenia can be the cause of hissing parasigmatism, softened pronunciation of [T] and [D].
Children suffering from hearing loss often have voicing defects, voiced consonants are replaced by deaf ones: [B-P], [V-F], [G-K], [D-T], [F-Sh], [Z-S ]. Due to the inaccessibility of hearing high tones, explosive consonants are often pronounced instead of whistling (“tooth” - “oak”, “sledge” - “tanks”). Hissing are replaced by whistling, affricates - their elements. Sound substitutions in oral speech are transferred to writing in the form of letter substitutions.
If there are sound substitutions in the speech of a child or an adult, the diagnosis is built taking into account the anamnesis and objective data. A speech therapist conducts a detailed study of speech function, medical specialists (audiologist, orthodontist) - the state of the auditory analyzer, dentoalveolar system:
Phonemic disorders that occur in children with physiological dyslalia do not require speech therapy intervention. Correction of pronunciation errors caused by other speech disorders is carried out in the following areas:
Of the methods of speech therapy influence, articulatory gymnastics, finger gymnastics, logomassage are used. In severe pathologies of speech, affecting not only the sound side, but also its other components, work is underway on all disturbed processes: prosody, voice, vocabulary, grammar, vocabulary, speech understanding in general.
Correction of malocclusion can be carried out by various methods. It depends on the type of disorder, age, severity of the problem. At preschool age, functional orthodontic appliances and myogymnastics are widely used. With a permanent bite, treatment is carried out with the help of braces, aligners, and, if necessary, orthognathic operations are performed.
Rehabilitation of persons with hearing loss is carried out through hearing aids. After the selection and adjustment of the hearing aid, such children need classes with a deaf teacher and a speech therapist.