What Is A Speech Impediment?

Communicating with the people around us is a fundamental part of human interaction and connection. For some people, this communication can be difficult. Speech impediments can affect our ability to converse effectively with others and cause feelings of low self-confidence. 

A speech impediment is a disruption in normal speech.1 It affects a person’s ability to produce the correct sounds and movements required for speech. Some examples of speech impediments are stuttering and apraxia. Speech impediments can affect both adults and children. They can impact learning, reading and social interaction.2 Early treatment, often with speech therapy, can increase the chances of speech improvement. 

Common examples of speech disorders include:


Dysarthria is a speaking difficulty due to weakness in the muscles used for speech. It results in slow, slurred, or unclear speech. It is a motor speech disorder usually caused by nervous system disorders or damage to the brain. Some conditions that can lead to dysarthria are Parkinson’s disease, multiple sclerosis, stroke and cerebral palsy. Dysarthria can also happen as a side-effect of certain medicines. 

Other symptoms include:

  • Monotone speech 
  • Nasal, raspy, or strained voice 
  • Difficulty moving your tongue, mouth, or lips
  • Speaking too loudly or too quietly 
  • Speaking too slowly or too fast

A person with dysarthria will usually be referred to a speech and language therapist (SLT). A therapist may help you practice slowing down your speech or use techniques to improve your breathing to facilitate clear, loud speech.

Verbal dyspraxia 

Verbal dyspraxia, also known as apraxia or childhood apraxia of speech (CAS), affects physical coordination. People with verbal dyspraxia have difficulty coordinating the muscles needed to produce clear speech. To speak correctly, the brain has to send messages to the speech muscles to move. In verbal dyspraxia, this communication is affected.  

Symptoms of verbal dyspraxia are:

  • Struggling to pronounce words correctly
  • Using a limited range of consonants and vowels
  • Pausing or hesitating during a speech 
  • Pronouncing the same word correctly and then incorrectly

A person with verbal dyspraxia will usually be referred to as SLT. Verbal dyspraxia can occur alone but is often associated with other speech disorders like dysarthria and aphasia.


Aphasia disrupts speech due to damage in the brain areas involved in language, usually after a stroke or brain injury. People with aphasia can have trouble with reading, listening, speaking, and writing. Aphasia doesn’t impact intelligence, but it can affect a person’s ability to communicate their thoughts well. It can affect people of all ages but is more common in those over the age of 65. This is because strokes tend to affect older people. 

A person with aphasia may:

  • Put words together incorrectly 
  • Use the wrong sounds in a word
  • Not understanding other people’s conversations
  • Speak in sentences that don’t make sense


Stammering, also known as stuttering, affects the flow of speech. People who stammer repeat sounds, syllables, or words. Stammering usually starts in early childhood, when it is called developmental stammering. The exact cause of developmental stammering is not yet known; however, there is a genetic link. Studies indicate that around 60% who have a stammer also have a family member who stammers or used to stammer. In some, it may start later in adulthood, which is when it is referred to as acquired or late-onset stammering. 

Stammering is more common in people assigned male at birth (AMAB) than people assigned female at birth (AFAB). Approximately 75% of people with a stammer are AMAB. The severity of a stammer can change over the course of life. Some may find they have periods where they stammer more often and periods where they stammer less. Some people may stammer less as they get older as well.

Stammering is when a child or adult:

  • Repeats sounds or syllables 
  • Makes sounds longer
  • Has words that get stuck or don’t come out 

Types of speech impediments

Speech impediments can affect voice, fluency and articulation. The main categories of speech impediments are:

  • Articulation disorders: These occur when a person has difficulty producing the motor movements required for speech. They typically affect children but can impact adults who have suffered from brain injury or stroke. Individuals with articulation disorders may show omissions, substitutions, or additions of sound in their speech. These disorders tend to be more common in children AMAB than children AFAB.
  • Fluency disorders: These interrupt the continuous flow of speech. The most common examples of fluency disorders are stuttering and cluttering. Cluttering is when a person speaks fast and merges their words together. They may also say ‘uh’ often.
  • Voice disorders: These change how the voice sounds. They affect the larynx. With voice disorders, the voice may be hoarse, raspy, or suddenly change in pitch. They may be caused by vocal nodules or cysts, or weakness of the vocal folds.
  • Resonance disorders: These are when too much air goes through the nose when speaking. This makes the voice sound more nasal. Common types of resonance disorders include hypernasality, hyponasality and cul-de-sac resonance. 

Causes of speech impediments

Understanding the cause of an impediment can help identify the best treatment for it. Sometimes, speech impediments may have an unknown cause. Some known causes include:

  • Genetic factors
    • Children are more likely to develop speech disorders if they have a parent who currently is, or has experienced one.3 Some language disorders can also be genetic, like hereditary ataxia, which can cause slow and unclear speech. 
  • Delayed speech development
    • Sometimes, children can show delays in reaching developmental milestones. These developmental delays can affect motor skills, cognitive abilities, or speech.  
  • Neurological conditions
    • Traumatic brain injury or stroke can impact the brain’s ability to control the muscles required for speech, resulting in impediments.4 People with conditions like autism or dementia may also develop speech impediments.
  • Hearing loss
    • Hearing sounds is an important part of learning to speak. People with hearing loss may find it difficult to produce different speech sounds and learn new words.
  • Emotional trauma or stress
    • Some people develop impediments like a stammer in response to trauma. Adults can develop a stammer after periods of intense stress.

Emotional impact of speech impediments  

Communicating skills is essential for self-expression and building healthy relationships. Often, people with speech impediments can have feelings of low self-esteem.5 They may withdraw and speak less often. Issues of socialising can lead to feelings of loneliness and isolation. 

People with speech impediments know what they want to say, but have a struggle forming the speech sounds to say the words and sentences. As a result, speech impediments can be incredibly frustrating. 

Diagnosis and assessment 

Diagnosis usually involves a referral to a speech and language therapist (SLT). SLTs will review a patient's medical and family history. They will check for other underlying conditions, like autism, that may result in an impediment. A hearing test might also be carried out to rule out hearing loss as a cause. 

Tools and techniques SLTs may use to inform a diagnosis are:

  • The Leiter International Performance scale-3 is a nonverbal test that measures cognitive ability. 
  • The Goldman-Fristoe Test of Articulation 3 (GFTA-3) which tests consonant sound articulation. It uses engaging images to prompt responses that include the major speech sounds.  
  • The Arizona Articulation and Phonology Scale 4th Revision (Arizona-4) is a test that evaluates articulatory and phonological skills.


Researchers emphasise the impact of early intervention on improving the outcome for people with speech impediments. Treatment methods will depend on the type and severity of the speech impediment. For those with impediments caused by cleft lip and palate, surgery might also be a treatment option. Some impediments may not require treatment, as some children can outgrow them. Speech therapy involves exercises that allow patients to practice producing certain sounds or to help find alternative ways of communication for people with severe impediments. 

Some treatment therapies used by SLTs include: 

  • Target selection: Practicing specific speech sounds or words chosen by an SLT. These can vary and may be based on how frequent the sounds are in the patient’s language or the patient’s general speaking ability. 
  • Contextual utilisation: This approach focuses on understanding how sounds are produced in different syllables.
  • Contrast therapy: Uses contrasting word pairs to emphasise the different sounds that need to be produced to differentiate the words from each other. An example of a word pair can be “pot” vs “spot” or “tea” vs “key.”
  • Oral-motor therapy: Weakness in the oral-motor muscles may cause poor articulation, so this therapy focuses on strengthening and improving the control of oral muscles.  


Speech impediments, like dysarthria and stammering, affect how a person is able to produce the sounds needed for speech. They can be caused by many factors, such as neurological conditions or hearing loss, though sometimes the cause is not always known. Children can grow out of milder speech impediments. Speech therapy can help improve speech for some, while individuals with a cleft lip and palate may benefit from surgery. Early diagnosis and intervention are crucial and can have a big impact on improving communication, learning and overall quality of life. 


  1. Sheikh SA, Sahidullah M, Hirsch F, Ouni S. Machine learning for stuttering identification: review, challenges and future directions [Internet]. arXiv; 2022 [cited 2023 Oct 13]. Available from: http://arxiv.org/abs/2107.04057
  2. Feldman HM. Evaluation and management of language and speech disorders in preschool children. Pediatrics In Review [Internet]. 2005 Apr 1 [cited 2023 Oct 13];26(4):131–42. Available from: https://publications.aap.org/pediatricsinreview/article/26/4/131/61533/Evaluation-and-Management-of-Language-and-Speech
  3. Kang C, Drayna D. Genetics of speech and language disorders. Annu Rev Genom Hum Genet [Internet]. 2011 Sep 22 [cited 2023 Oct 13];12(1):145–64. Available from: https://www.annualreviews.org/doi/10.1146/annurev-genom-090810-183119
  4. Basilakos A, Fridriksson J. Types of motor speech impairments associated with neurologic diseases. In: Handbook of Clinical Neurology [Internet]. Elsevier; 2022 [cited 2024 Feb 2]. p. 71–9. Available from: https://linkinghub.elsevier.com/retrieve/pii/B9780128233849000049
  5. Krueger BI. Eligibility and speech sound disorders: assessment of social impact. Perspect ASHA SIGs [Internet]. 2019 Feb 26 [cited 2023 Oct 13];4(1):85–90. Available from: http://pubs.asha.org/doi/10.1044/2018_PERS-SIG1-2018-0016
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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