Speech Sound Disorders: Causes, Treatment and Strategies

By Wellness Hub

Last Updated: October 14, 2023

Speech is one of the basic forms of communication. Speech helps to verbally express and exchange an individual’s thoughts, feelings, and ideas with others. While everyone learns to speak from an early age, some individuals find it difficult. They would start to speak at a later age or find it difficult to pronounce words. The difficulties that won’t let you make correct speech sounds are called speech sound disorders. For example, saying “wabbit” instead of “rabbit” or facing trouble pronouncing “th” in “this” and so on comes under these speech problems. Hence, Speech sound disorders, also known as articulation disorders or phonological disorders, are conditions that affect a person’s ability to produce speech sounds correctly. 

Speech sound disorders can impact an individual’s intelligibility, social interactions, and communication abilities. In this article, we will explore the various aspects of speech sound disorders, including their causes, types, and potential treatments.

What are Speech Sound Disorders?

Speech sound disorders refer to issues that occur during the production of speech sounds, also known as phonemes. Speech sound disorders can affect a person’s intelligibility. Their speech makes it difficult for others to understand.

Types of Speech Sound Disorders

Speech sound disorders can be of two types:

  • Functional speech sound disorders
  • Organic speech sound disorders.
Speech Sound Disorders

Functional speech sound disorders

Functional speech sound disorders are two types:

  1. Articulation disorders
  2. Phonological disorders
Articulation DisordersPhonological Disorders
1. Errors at the phonetic/motoric level (difficulty producing sounds)
2. 1-2 errors that are substituted or distorted, typically in a predictable way
3. More common in older students.
1. Errors at the phonemic/linguistic level (difficulty organizing sounds)
2. Groups of sounds or types of syllable structures are omitted, swapped, or simplified which can be consistent or inconsistent
More common in younger students.

It is often difficult to clearly differentiate between articulation and phonological disorders; therefore, many researchers and clinicians prefer to use the broader term “speech sound disorder” when referring to speech errors of unknown cause.

Articulation disorders (Phonetic Disorders)

Articulation disorders refer to errors in the production of speech sounds. These speech sound issues can be identified in many ways, including

  • Substitutions (replacing one sound with another, for example: wabbit for rabbit )
  • Omissions (leaving out a sound from the word, for example, bo for boat)
  • Distortions (altering the sound quality of a word, for example: shlip for sip)
  • Additions (inserting extra sounds in the word, for example, “Ismayil” for “Smile”)

Any type of such issues can be identified as problems in Articulation.

Phonological disorders (Phonemic Disorders)

Phonological disorders refer to the linguistic aspects of speech. These disorders focus on predictable, rule-based errors. The issue is more about systematic patterns of errors that affect an individual’s speech intelligibility. Examples of such disorders can be

  1. Assimilation (Actual sound is pronounced like a neighboring sound)
  2. Cluster reduction (grouping neighboring consonants and reducing to one sound)
  3. Final consonant deletion (omitting final consonant sound in a word)
  4. Backing (replacing the sounds produced at the front of the mouth with the sounds produced at the back of the mouth)
  5. Fronting (replacing the sounds produced at the back of the mouth with the sounds produced at the front of the mouth)
  6. Initial consonant deletion (omitting the initial consonant sound of a word)

Every individual with this disorder doesn’t produce the same error. These patterns can vary from person to person. Phonological disorders are considered both speech and language disorders because it is the language system that is affected, but they are also speech sound disorders in that the errors relate to the use of phonemes (speech sounds). This makes it different from specific language impairments, which are primarily disorders of morphology (word structure), syntax (grammar), semantics (meaning), and pragmatics (usage) of language rather than the sound system.

Organic speech sound disorders

Organic speech sound disorders include those resulting from issues relating to various areas. They can be

  • Motor/Neurological disorders (relating to execution, such as Dysarthria, or planning, such as Apraxia) Certain neurological conditions, such as apraxia of speech or dysarthria, can impact the motor control and coordination necessary for precise speech sound production.
  • The muscles involved in speech need to move in a coordinated manner in order to produce Speech Sounds. These movements are controlled by the brain and are also dependent upon speech muscle strength.
    • In Apraxia, the speech muscles are normal and of normal strength but the brain signals that control movements of these muscles during speech become abnormal
    • In Dysarthria, the brain signals that control the movement of speech muscles during speech are normal but speech muscles are weak and not able to move
  • Structural disorders (relating to issues of cleft palate or other orofacial abnormalities or structural deficits due to trauma or surgery) Some individuals may have physical abnormalities in their oral structures, such as cleft palate or tongue-tie, which can affect speech sound production.
  • Sensory/Perceptual disorders (such as Hearing impairment) Problems in hearing and auditory processing can make it challenging to perceive and produce speech sounds accurately.
Motor/Neurological ConditionStructural DeficitsSensory Perceptual Deficits
Apraxia of Speech (AOS) or Acquired Apraxia of Speech is an acquired oral motor speech disorder affecting an individual’s ability to translate conscious speech plans into motor plans, which results in limited and difficult speech ability. AOS affects wilful or purposeful movement patterns and usually also affects automatic speech. Apraxia of speech can be caused by impairment to parts of the brain that control muscle movement and speech. Individuals with AOS have difficulty connecting speech messages from the brain to the mouth. AOS is a loss of prior speech ability resulting from a brain injury such as a stroke, trauma, progressive illness or tumor. AOS can affect a person at any age although it mostly typically occurs in adults.Orofacial anomalies Structural anomalies of the oral and facial structures, such as cleft lip or palate, may affect the articulation of speech sounds. These anomalies can impact the movement and coordination of the articulators, resulting in speech production difficulties.Hearing loss or auditory processing disorders, can lead to difficulties in perceiving and discriminating between speech sounds accurately, impacting the ability to produce sounds correctly.
Childhood Apraxia of Speech (CAS) is an inability to utilize motor planning to perform movements necessary for speech during a child’s language-learning process. The cause may be genetics and sometimes there is no observable cause. Although the causes may differ between AOS and CAS, the main characteristics and treatments are similar.Dental abnormalities  Malocclusions, missing teeth, or other dental anomalies can affect the positioning of the tongue, lips, and teeth, leading to difficulties in producing specific speech sounds. For example, dental malocclusions can influence the production of sounds like /s/ and /z/.
Dysarthria is a motor speech disorder characterized by difficulty articulating sounds. The difficulty in articulation does not occur in planning the motor movement, as happens with Apraxia of Speech. Instead, dysarthria is caused by the inability or weakness of the muscles in the mouth, face, and respiratory system. Dysarthria can result from congenital conditions, or it can be acquired at any age as the result of neurological injury, disease, or disorder.Anatomical variations: Variations in the size, shape, or structure of the oral cavity, palate, or pharynx can impact the resonance and articulation of speech sounds. These variations can affect the quality and clarity of speech production.
Anatomical abnormalities: Unusual anatomical structures, such as enlarged tonsils or adenoids, can obstruct the airflow, leading to abnormal speech sound production.

Causes of Speech Sound Disorders

Speech sound disorders can have various causes, and they may result from a combination of factors. Speech sound disorders can also result from environmental influences, like exposure to non-standard dialects or a lack of speech modeling in the home. When people with speech issues are around, it can be understood that children learn to speak in the same way.

Developmental factors

Many children go through a phase of speech sound errors as they learn to speak, but some continue to struggle with the correct production of sounds longer than expected. These may be categorized as developmental speech sound disorders.

Structural or physiological factors

Physical abnormalities, such as cleft palate or missing teeth, can affect the production of speech. These again refer to developmental factors affecting speech production.

Hearing impairments

Hearing loss can impact an individual’s ability to hear and produce speech sounds correctly, especially if the hearing loss occurs during critical periods of language development.

Neurological conditions

Certain neurological conditions, such as apraxia of speech or dysarthria, can lead to speech sound disorders. Apraxia involves difficulty planning and coordinating the movements needed for speech, while dysarthria results from weakness or paralysis of the speech muscles.

Treatment and Therapies

Treatment for speech sound disorders typically involves a speech-language pathologist providing speech therapy. The SLP assesses the individual’s speech patterns, identifies specific sound errors or patterns, and develops a tailored treatment plan. Therapy may involve exercises to improve articulation, practice with specific speech sounds, and strategies to correct phonological patterns.

Early intervention is crucial for children with speech sound disorders, as addressing the issue during developmental years can lead to better outcomes. For adults with acquired speech sound disorders due to injury or illness, rehabilitation by an SLP can also be effective in improving speech intelligibility and communication abilities.

Treatment Strategies

Treatment Strategies for speech sound order

The treatment of speech sound disorders typically involves the expertise of a speech-language pathologist (SLP). The specific therapy approach depends on the individual’s age, the severity of the disorder, and the underlying causes. 

The common treatment strategies include:

Articulation Therapy

During articulation therapy, a speech therapist focuses on teaching the correct placement and movement of the articulators (tongue, lips, etc.) This helps to produce specific speech sounds as accurately as possible.

Phonological Therapy

During phonological therapy, specific patterns of errors are addressed. An individual is taught the rules and patterns of their language’s sound system.

Auditory Discrimination Training

This training involves hearing and distinguishing between different speech sounds correctly. Discriminating between the actual speech sound and the pronounced sound will help an individual to learn better.

Motor Speech Therapy

During motor speech therapy, an individual is trained to gain control over motor functions of speech. The neurological conditions affecting speech are addressed during motor speech therapy.

Family Involvement:

In many cases, involving the family in therapy can help reinforce progress and encourage consistent practice at home.

Though speech sound disorders impact a person’s ability to communicate effectively, early intervention strategies help significantly improve speech. Early intervention helps achieve the best outcomes, making it important to promptly address any concerns about speech sound disorders.