Motor Speech Disorders Explained: Dysarthria and Apraxia of Speech — A Complete Guide

Motor speech disorders are difficulties with planning or physically producing speech that happen when the brain or nerves are affected. In dysarthria, the muscles used for speaking are weak, slow or poorly coordinated, so speech can sound slurred or unclear. In apraxia of speech, the muscles themselves can work, but the brain’s planning of speech movements is disrupted, so sounds come out inconsistently and words can feel hard to launch.

If you are reading this after a stroke, a brain injury or a new diagnosis — your own, or someone you love’s — you may be trying to understand why speech that used to be automatic now takes so much effort. Perhaps the words are there, in the mind, but they come out muffled, tangled or not at all as intended. Perhaps family members lean in and ask for repeats, and phone calls have become something to dread.

This guide explains motor speech disorders in plain language: how speech is normally produced, what dysarthria and apraxia of speech each involve, how they differ from each other and from aphasia, and what assessment, therapy and everyday support can look like. It cannot say what is causing one person’s speech difficulty, or what will help them most — only an assessment can do that — but it can help you understand what is happening and feel clearer about the next step.

Key Takeaways

• Motor speech disorders affect the movements of speech, not a person’s intelligence, knowledge or personality.
• Dysarthria happens when the speech muscles are weak, slow or uncoordinated, so speech may sound slurred, quiet, strained or uneven.
• Apraxia of speech happens when the brain’s planning of speech movements is disrupted; the muscles can work, but sounds come out inconsistently.
• Motor speech disorders are different from aphasia, which affects language itself — although the two can occur together after the same injury.
• A speech and language therapist can assess speech and work with the person and their family on strategies, practice and communication goals that matter in everyday life.
• Communication partners make a real difference: patience, time, a quieter room and honest checking help far more than finishing sentences or pretending to understand.

On this page

• How speech is produced: a three-step picture
• Dysarthria: when the speech muscles are affected
• Apraxia of speech: when the brain’s planning of speech is disrupted
• Dysarthria and apraxia of speech side by side
• Motor speech difficulties in children
• How motor speech disorders differ from aphasia
• When motor speech disorders and aphasia occur together
• Everyday effects of a motor speech disorder
• Assessment: understanding the difficulty
• Therapy and support approaches
• Supporting communication at home
• Emotional wellbeing
• When to seek help
• Questions to ask a therapist
• Frequently asked questions
• Related guides

How speech is produced: a three-step picture

Speaking feels effortless when it works, but it is one of the most intricate movements the body makes. Dozens of muscles must move in precise sequence, timed to fractions of a second. A simple way to picture it is in three steps:

1. The brain plans the message and the movements. First, you decide what you want to say. Then, a part of the brain works out the exact sequence of movements needed to produce those sounds, in that order, at that speed — a kind of movement programme for the mouth.
2. Signals travel from the brain to the muscles. The plan is sent as electrical signals along nerves to the muscles of speech. If the signals are weak, mistimed or interrupted along the way, the movements that arrive are weak, slow or poorly coordinated.
3. The speech muscles move. Breathing muscles push air up from the lungs. The voice box (larynx) turns that air into voice. The tongue, lips, jaw and soft palate shape the voice into sounds and words, while the cheeks and throat help control the airflow, including whether sound escapes through the nose.

A motor speech disorder is a difficulty at step 1 or steps 2 and 3 — with the planning of the movements, or with carrying them out. The words and ideas themselves (the language) may be completely intact. That is why a person with a motor speech disorder often knows exactly what they want to say: the difficulty lies in getting the mouth to produce it clearly.

This three-step picture also explains the two main types of motor speech disorder. When the planning step is disrupted, the result is apraxia of speech. When the signals or the muscles are affected, the result is dysarthria. Some people have elements of both.

Dysarthria: when the speech muscles are affected

Dysarthria is a motor speech disorder in which the muscles used for speaking are weak, slow, stiff, unsteady or poorly coordinated. The brain may form the plan correctly, and the person may know exactly what they want to say, but the muscles cannot carry the plan out precisely. The result is speech that sounds different from before and can be hard for listeners to understand.

How dysarthric speech can sound

Dysarthria does not sound the same in everyone, because it depends on which muscles are affected and how. In general terms, speech with dysarthria may be:

• Slurred or imprecise, as if the sounds are blurred together — consonants are often the hardest hit, and clear consonants are what make speech easy to follow.
• Slow, or sometimes unusually fast and rushed, with words running into one another.
• Quiet or fading, if breath support or voice strength is reduced, so the ends of sentences trail away.
• Strained, tight or hoarse, if the voice muscles are tense or working unevenly.
• Nasal, if air escapes through the nose during speech when it should not, or too flat and monotone if pitch and emphasis are hard to vary.
• Uneven in rhythm, with pauses in unexpected places, short rushes of words, or extra effort visible in the face and neck as the person speaks.

Speech may also be more difficult when the person is tired, unwell or in a noisy place, and clearer at rested, quiet times of day. Eating, drinking and swallowing use some of the same muscles and pathways as speech, so speech and swallowing difficulties can travel together; anyone who notices coughing, choking or difficulty with food or drink should raise it promptly, because swallowing needs its own assessment.

What can cause dysarthria

Dysarthria happens when the brain, or the nerves running between the brain and the speech muscles, are damaged or affected by illness. In general terms, it can occur:

• After a stroke, when the affected area of the brain controls movement or sends signals to the speech muscles.
• After a head injury or brain surgery.
• In Parkinson’s, where changes in movement control can make speech quieter, faster or less clearly articulated over time.
• In other neurological conditions that affect movement, muscle strength or coordination, including conditions that affect the nerves or muscles directly.

The cause matters for the medical team looking after the person, and it shapes what therapy focuses on — but the starting point is the same: a speech and language therapy assessment to understand how speech has been affected and what can help.

Apraxia of speech: when the brain’s planning of speech is disrupted

Apraxia of speech — sometimes called acquired apraxia of speech in adults — is a difficulty with planning and programming the movements of speech. The muscles of the tongue, lips and jaw are not weak: the person can often eat, smile, cough and move their mouth for everyday actions without difficulty. The problem appears when those same muscles are asked to produce speech, because the brain’s movement programme for sounds and syllables has been disrupted.

How apraxia of speech can sound

The hallmark of apraxia of speech is inconsistency. Speech may involve:

• Errors that vary from try to try. The same word may come out differently each time — nearly right once, tangled the next. This inconsistency is one of the features that helps a therapist distinguish apraxia from dysarthria.
• Groping for sounds. The person may visibly or audibly search for the right mouth position, starting a word, stopping, and trying again — sometimes several times.
• Difficulty getting started. The first sound of a word or sentence can be the hardest, even when the rest follows more easily.
• Longer words and sentences are harder. Short, familiar words may come out clearly, while a long word or a new sentence breaks down.
• Automatic speech is easier than deliberate speech. Well-worn phrases — greetings such as “good morning”, counting, or the words of a familiar song — often flow surprisingly smoothly, because they are stored as ready-made routines. But a sentence the person has chosen and constructed for the moment may tangle, because it has to be freshly programmed.
• Distorted sounds and disrupted rhythm. Sounds may be substituted or distorted, and the natural melody and stress of speech can sound flattened or uneven, with pauses between syllables.

People with apraxia of speech usually know when they have made an error, and many can hear that a word came out wrong even when they cannot immediately produce it correctly. That awareness, combined with the struggle, can be deeply frustrating: the person knows what clear speech should sound like, because they can still hear it in their mind.

What can cause apraxia of speech

Acquired apraxia of speech most often follows a stroke that affects the areas of the brain involved in planning speech movements. It can also follow a head injury or other injury to those areas. It very often occurs alongside aphasia, because the speech-planning and language areas of the brain sit close together and can be affected by the same injury — but it is a separate difficulty from aphasia, as the sections below explain.

Dysarthria and apraxia of speech side by side

The two disorders can sound alike at first listen — in both, listeners struggle to make out what is said. But their causes are different, and so is the help that supports them. This table gives a simple comparison.

Feature	Dysarthria	Apraxia of speech
Where the difficulty lies	The speech muscles themselves: weakness, slowness, stiffness or poor coordination	The brain’s planning and programming of speech movements
Strength of the speech muscles	Reduced or uncoordinated — everyday mouth movements may also be affected	The muscles can be strong; non-speech movements such as smiling or chewing are often unaffected
Consistency of errors	Fairly consistent — speech sounds similar from one try to the next	Inconsistent — the same word may come out differently each time
Typical sound of speech	Slurred, quiet, slow or fast, strained or nasal	Groping, distorted sounds, false starts, uneven rhythm
Automatic phrases	Affected in much the same way as other speech	Often noticeably easier than deliberate, chosen speech
Awareness of errors	The person usually knows speech is unclear	The person usually hears their own errors clearly, which can add to frustration

In real life, the picture is rarely as tidy as a table. A single injury can affect both the planning system and the muscles, so a person may have apraxia of speech and dysarthria together, each contributing to how speech sounds. Sorting out which difficulties are present, and how much each contributes, is part of what a speech and language therapy assessment is for.

Motor speech difficulties in children

Motor speech disorders are spoken about most often in adults, because stroke and neurological illness are common causes — but children can have motor speech difficulties too. The best known is childhood apraxia of speech, in which a child’s brain has difficulty planning the movements for speech even though the muscles themselves are not weak. A child with this difficulty may say the same word differently each time, struggle to copy sounds and words, and find longer words especially hard.

This guide focuses on adults. If you are a parent wondering about your child’s speech, you can read more in our guides to childhood apraxia of speech and speech sound disorders in children, in the children’s section of this site.

How motor speech disorders differ from aphasia

Motor speech disorders are often confused with aphasia, but they affect different systems, and the distinction matters:

• Aphasia is a difficulty with language — finding words, building sentences, understanding what is said, reading and writing. The message itself is hard to form or decode.
• A motor speech disorder is a difficulty with the movements of speech — planning them, or carrying them out. The message is formed; producing it clearly is the problem.

Imagine typing a message on a keyboard. Aphasia is like losing some of the words of the language itself. Dysarthria is like a keyboard with weak, sticking keys — you know what you want to type, but the output comes out blurred. Apraxia of speech is like the instructions that tell the fingers which order to press the keys getting scrambled, so the same word comes out differently each time you type it.

A person with a motor speech disorder alone can know exactly what they want to say — every word of it — and still be hard to understand, because the difficulty is in the physical delivery. Their understanding, reading and writing may be much less affected than their speech, though a therapist will check all of these, since difficulties often overlap.

When motor speech disorders and aphasia occur together

The brain areas that handle language, speech planning and movement sit close together, and a stroke or injury can affect more than one of them. This means combinations are common:

• Aphasia together with apraxia of speech — the person has difficulty finding words and planning the movements to say them.
• Aphasia together with dysarthria — word-finding is difficult, and the speech that does come out is weak or slurred.
• All three together, each contributing its own layer of difficulty.
• A motor speech disorder on its own, with language largely unaffected.

This is one reason two people with the “same” diagnosis on paper can sound very different, and why therapy has to be shaped around a careful assessment of the individual. It also explains why a person’s speech can be far worse than their understanding, or the other way round — the systems are separate, and each needs its own support.

Everyday effects of a motor speech disorder

The effects of a motor speech disorder reach well beyond how speech sounds. Families and survivors often describe these everyday consequences:

• Being misunderstood. Listeners ask for repeats, guess wrongly, or give up — and the person may stop trying to say what they meant. Being misheard repeatedly, by strangers and loved ones alike, is wearing in a way that is hard to appreciate until it happens to you.
• The telephone is especially hard. On the phone there are no lip movements, gestures or facial expressions to help the listener, and no faces to read in return. Many people find phone calls far harder than face-to-face conversation, and may avoid them entirely.
• Talking is tiring. Speech that once took no thought now demands concentration and physical effort. Long conversations, group settings and busy days can leave a person exhausted, and their speech is often clearest when they are rested.
• Background noise defeats speech. Pubs, cafés, family gatherings and open-plan rooms — places where everyone talks over everyone else — become some of the hardest environments there are.
• Social withdrawal. It is natural, though painful, to start declining invitations, letting others order in restaurants, or handing the phone to a partner. Over time this can shrink a person’s world and their confidence within it.
• Work and roles change. Jobs that involve talking — meetings, presentations, answering phones, teaching, dealing with the public — can become difficult or exhausting, and returning to them usually needs thought and support.
• Family strain. Partners and family members can slide into the role of interpreter, speaking for the person in shops and appointments. It helps to talk openly about when interpreting is welcome and when the person would rather take longer and speak for themselves.

Assessment: understanding the difficulty

An assessment by a speech and language therapist is the starting point for support. It is a gentle, conversational process — there are no painful procedures involved — and it is designed to build a clear picture of how speech has been affected. It may include:

• Talking together. The therapist will want to hear natural conversation, and to talk with you (and, where you wish, your family) about when the difficulty began, how speech has changed, and what matters most to you in everyday life.
• Listening carefully to speech. The therapist listens to how sounds, words and sentences are produced — how consistent the errors are, how speech changes with longer or more complex words, and how easy speech is to follow overall.
• Looking at how the mouth moves. The therapist may ask the person to make simple movements — opening the mouth, moving the tongue, smiling, coughing — and to repeat sounds, syllables and words. This helps separate difficulties of muscle strength and coordination from difficulties of planning.
• Checking related areas. Because motor speech disorders can travel with other difficulties, the therapist will usually check understanding, language, reading and writing as well, and will ask about eating and drinking. Where needed, they can liaise with the wider medical team.
• Talking about intelligibility. A central question is how well the person’s speech is understood — by family who know them well, and by people meeting them for the first time. A difficulty might be described in plain words as mild, where speech is mostly clear but tires or blurs at times, through to severe, where even familiar listeners find speech very hard to follow. Knowing where a person sits on that scale helps shape realistic goals.

After the assessment, the therapist explains what they found in plain language, and agrees goals with the person — practical goals that matter in real life, such as being understood on the phone by family, ordering independently in a café, or managing conversation in a small group.

Therapy and support approaches

Therapy for motor speech disorders is built around the person’s own goals, and it usually combines work on speech itself with strategies that make communication succeed in daily life. Approaches are individual — what helps one person may not suit another — and a therapist will explain and agree the plan with you. In general terms, therapy might involve the following.

For dysarthria: making the most of the speech muscles

• Slowing down. Speaking more slowly, with deliberate pauses, gives the muscles time to reach their targets and gives listeners time to take speech in. It is often the single most powerful strategy, and it takes practice to make it a habit.
• Over-articulating. Exaggerating mouth movements slightly — opening the mouth more, making consonants crisper — can sharpen clarity, a little like speaking as if the listener is slightly further away than they are.
• Breath support and loudness. Therapy may work on using the breath well: sitting upright, breathing in before starting, speaking in shorter phrases with pauses to re-breathe, and building a stronger, steadier voice volume where reduced loudness is part of the difficulty.
• Exercises, explained carefully. Some therapy programmes include exercises for the speech muscles. These are mentioned here only as an educational overview: exercises are not suitable for everyone, the evidence for any particular exercise depends on the individual difficulty, and any exercise should be individually assessed, taught and supervised by a qualified speech and language therapist rather than copied from general information. This matters, because the wrong exercise, too much exercise, or exercise that causes fatigue can be unhelpful for some people.
• Pacing and energy management. Because speech often deteriorates with tiredness, planning important conversations for rested times, and resting the voice between demands, can be part of the plan.

For apraxia of speech: rebuilding the movement programmes

• Intensive, repeated practice of sounds and words. Therapy often involves practising target sounds, syllables and words many times, in a structured way, so the brain’s movement programmes for them become more reliable. Short, frequent practice usually suits this better than occasional long sessions.
• Working from the achievable towards the harder. Practice might begin with sounds and words the person can already manage, then build gradually towards longer words, phrases and sentences used in real life.
• Rhythm and melody-based approaches. Some therapy uses rhythm, timing cues or a sing-song, melodic pattern to help speech get started and flow, then gradually fades the melody back towards natural speech. Singing familiar songs can also be a way in, because familiar melodies and lyrics are stored as routines.
• Building functional phrases. Practice often focuses on the phrases a person most needs — greeting family, asking for help, answering the phone, saying names of loved ones — so that progress shows up in daily life, not only in exercises.
• Using writing and gesture as scaffolding. Writing the first letter of a stuck word, tapping out syllables, or gesturing can help the planned movements unlock, and therapists may build these cues into practice.

Communication aids and partner support, for both

Alongside work on speech itself, therapy may introduce other ways to support communication. These are described here by type only, because the right choice depends on the individual:

• Alphabet boards and letter charts, where the person points to the first letter of each word as they speak. This slows speech down and gives the listener a strong clue, and it can transform intelligibility.
• Writing and drawing, with a notebook or whiteboard kept to hand for key words when speech breaks down.
• Text-to-speech tools — technology, described by type, that speaks typed text aloud — for situations where speech is very hard to follow or the person is very tired.
• Communication partner strategies, where the therapist coaches family and friends in the habits described in the next section. In motor speech disorders, the listener’s behaviour is half the conversation, and training it is a legitimate and powerful part of therapy.

Supporting communication at home

Families and friends often ask what they can do. The honest answer is: a great deal, and most of it is simple. These habits help conversation succeed:

• Face each other, in good light. Sit or stand where you can see the person’s face, and keep your own face visible too. Lip movements and expressions carry a lot of meaning, in both directions.
• Reduce background noise. Turn off the television or radio during important conversations, close a window onto a busy street, and choose the quiet corner rather than the middle of the room.
• Give time. Resist finishing sentences, guessing the ending, or answering for the person. Rushing adds pressure, and pressure makes speech harder. Count to ten silently before offering help if a word is stuck — and only help in the way the person prefers.
• Confirm rather than pretend. Pretending to understand feels kind in the moment but leads to real confusion later. It is far more helpful to say, honestly and warmly: “I got the first part but missed the end — could you say that bit again?” Repeating back the part you did understand helps the person build on it.
• Ask one thing at a time. Short questions, asked one at a time, and yes/no questions where they fit, are easier to answer and easier to check than long, layered ones.
• Use every channel. Encourage gesture, pointing, writing a key word, or spelling the first letter aloud. Any route to being understood counts as success.
• Pick your moments. Long or important conversations go better when the person is rested. It is fine to agree, kindly, to come back to a topic later in the day.
• Let the person decide how much help they want. Some days a person wants their partner to interpret; other days they want time to manage alone. Asking, and respecting the answer, protects dignity and independence.

Emotional wellbeing

A motor speech disorder changes something most people think of as part of who they are: their voice, their fluency, their ability to join in, joke, argue and chat. It is entirely understandable for that to affect mood and confidence.

Frustration is almost universal. A person may know precisely what they want to say, hear how unclear it sounds, and watch a listener fail to follow — many times a day. Others may feel embarrassment in public, grief for the easy talker they were, or anger that something so basic has become so hard. Some withdraw from conversation to avoid the struggle, and that withdrawal can deepen low mood. Family members feel it too: the effort of listening, the sadness of conversations that no longer flow, and the guilt of sometimes getting it wrong.

If low mood, anxiety or loss of interest in things persists, it is worth raising with the person’s doctor or care team, because support is available and mood affects rehabilitation as much as rehabilitation affects mood. Many people also value meeting others in a similar position, through local or online peer support groups for people living with speech and communication difficulties after stroke or brain injury — being with people who understand without explanation can be a relief. For general information about stroke and its effects, you can also visit the American Stroke Association and the World Stroke Organization.

When to seek help

If speech has changed and has not been assessed, it is worth seeking advice. A speech and language therapy assessment can clarify what kind of difficulty is present and what support would help. Useful routes include:

• Your doctor. If speech has changed after a stroke, injury or illness, or if it is changing gradually over time, tell your doctor. Speech changes can be part of conditions that need medical investigation and ongoing care.
• Your existing care team. If you are already under a stroke, rehabilitation or neurology team, ask them about speech and language therapy — referral may be straightforward.
• Contacting a speech and language therapist directly. In many places you can arrange an assessment directly, without waiting for a referral.
• Sooner rather than later for gradual changes. If speech is slowly becoming quieter, less clear or more effortful over months, do not wait for it to resolve on its own — an assessment can clarify what is happening and what can help.

One situation is an emergency, and it is different from everything above. Slurred or disturbed speech can be a sign of a stroke, and a stroke needs emergency treatment. If speech suddenly becomes slurred or hard to understand, or there is sudden weakness of the face or arm, or the face droops on one side, call your local emergency number immediately. Do not wait to see whether it passes, and do not drive the person yourself if an ambulance is available. Sudden choking or difficulty breathing is also an emergency.

Questions to ask a therapist

If you are arranging an assessment, or preparing for a first appointment, these questions can help you get the most from it:

1. What kind of motor speech difficulty does the assessment suggest — dysarthria, apraxia of speech, or a mixture — and how does that show up in my speech?
2. How well can people who do not know me understand my speech, and what would help most with that?
3. What therapy approaches would you suggest for me, and what would practice between sessions involve?
4. Are there strategies or communication aids — such as an alphabet board — that could help me in everyday situations right now?
5. What can my family and friends do to support conversation, and can they be involved in sessions?
6. How will we set goals, and how will we review whether therapy is helping?

Frequently asked questions

Related guides

• Signs of dysarthria after stroke
• Dysarthria vs apraxia of speech: what is the difference?
• Aphasia: a complete guide for survivors, families and carers
• Support for adults: the For Adults hub
• Browse all conditions and topics

A gentle next step

If speech has become unclear, effortful or unreliable — for you or for someone you love — you do not have to sort it out alone. An assessment can clarify what kind of difficulty is present and what might help, and there is no obligation attached to asking. If you would like to talk about speech and what you have noticed, you are very welcome to get in touch online. There is no pressure: just a friendly first conversation, at your pace.

By Hamayal Adnan, Speech-Language Pathologist

This article is for general educational purposes only and is not medical advice. It does not replace an assessment by a qualified speech and language therapist or other healthcare professional. Every person is different. If you have concerns about speech, language, feeding or swallowing, please seek professional advice. In an emergency, call your local emergency number.