Understanding The Difference Between Apraxia Of Speech And Misarticulation
Author: Roselyn Mathew, Reg. CASLPO, Speech-Language Pathologist
Date: Wednesday, August 06, 2025
Table of Contents
Introduction
Clear speech is essential for everyday communication, yet many people struggle with speech sound disorders that make it difficult to be understood. Among these challenges, two often confused conditions are apraxia of speech and misarticulation. While both can result in unclear speech, they are fundamentally different in their causes and characteristics.
Apraxia of speech involves inconsistent errors and difficulty coordinating the precise movements needed for speaking, even when the person knows exactly what they want to say. On the other hand, misarticulation leads to predictable, repeated mistakes in producing specific sounds. These differences matter because they require distinct approaches to assessment and therapy.
We will discuss how these disorders present differently in everyday speech, how professionals identify them, and why tailored treatment is crucial for helping individuals improve their communication skills. Understanding these distinctions ensures better support for those affected, whether in clinical, educational, or personal settings.
Apraxia of speech (AOS)
Apraxia of speech (AOS) is a neurological motor speech disorder that disrupts the brain's ability to plan and sequence the precise movements needed for speech production. The condition occurs when the neural pathways responsible for coordinating speech movements malfunction, despite normal muscle strength and language comprehension.
Characteristics of AOS
Inconsistent Speech Errors: One hallmark of AOS is the unpredictable nature of speech errors. A person might say "television" correctly once but produce it as "tevision" or "telebin" on subsequent attempts.
Articulatory Groping: Individuals often show visible struggle as they attempt to position their lips, tongue, and jaw correctly. This groping reflects the brain's difficulty translating speech plans into precise movements.
Prosodic Abnormalities: Speech may sound robotic or monotone, with equal stress placed on each syllable.
Length and Complexity Effects: Longer words and complex phrases present greater challenges than shorter, simpler words.
Automatic Speech Preservation: Routine phrases like greetings or counting are typically clearer than novel, spontaneous speech.
Causes of AOS
AOS most commonly results from:
• Stroke (particularly affecting the left hemisphere)
• Traumatic brain injuries
• Neurodegenerative conditions
• Brain tumors
Misarticulation
Misarticulation refers to consistent, predictable errors in speech sound production. Unlike AOS, these errors are not caused by neurological motor planning difficulties but rather by structural, auditory, or learned factors.
Types of speech errors due to misarticulation
Substitutions: Replacing one sound with another (e.g., "wabbit" for "rabbit") • Omissions: Leaving out certain sounds (e.g., "ca" for "cat")
Distortions: Altered sound production (e.g., lateral lisp on "s" sounds) • Additions: Inserting extra sounds (e.g., "buh-lue" for "blue")
Causes of misarticulation
Structural
They are caused due to any structural defects seen at birth or can happen in the later years.
Cleft Lip/Palate
A cleft is an opening in the lip or roof of the mouth (palate) that fails to close during fetal development.
Dental Problems (Malocclusions)
Misaligned teeth (overbite, underbite) or missing teeth can block the tongue from making proper contact for certain sound
Tongue-Tie (Ankyloglossia)
A tight or short frenulum (the tissue under the tongue) restricts tongue movement.
Post-Surgical Changes
Surgeries to repair clefts or remove oral tumors can alter mouth anatomy.
Hearing loss
Hearing loss, particularly in high-frequency ranges, makes it hard to hear certain speech sounds, leading to mispronunciations.
Learnt behaviours
Certain sounds might have been incorrectly learned since childhood and can persist in adulthood.
Similarities in speech errors in AOS and misarticulation
The speech errors seen in AOS are quite similar to that seen in misarticulation. As discussed above, the same SODA errors are also seen here. These are:
Substitutions
Speech sounds can get substituted in words. The substitution can occur in initial, medial or in final word position. For eg. they might substitute the sound /k/ for /f/ and say cone instead of phone.
Omissions
Here, a sound might get deleted from a word. Again, the sound omission or deletion can occur in the initial, medial or final word position but it is usually omitted in the final word position.
Distortions
Sounds can get unclear or distorted. Eg. Having a distortion of the /s/ sound resulting in a lisp. Distortions are generally not seen in AOS but can happen though not commonly.
Additions
An additional sound is added. Eg. Saying falight instead of flight.
Differences seen in speech errors in AOS and misarticulation
Error Consistency
AOS: Speech errors are highly inconsistent and unpredictable, with the same word being pronounced differently each time it's attempted (e.g., saying "television" correctly once, then as "tevision" and later as "telebin" in subsequent attempts). This reflects the brain's difficulty in reliably planning speech movements.
Misarticulation: Errors follow consistent, predictable patterns where specific sounds are always mispronounced the same way (e.g., consistently substituting /w/ for /r/ in all words like "wabbit" for "rabbit"). These patterns typically follow developmental or structural limitations.
Automatic vs. Volitional Speech
AOS: Automatic, overlearned speech (such as counting, days of the week, or common greetings) remains relatively clear and fluent, while novel, purposeful speech shows significantly more errors. This demonstrates that stored motor programs are more accessible than new ones.
Misarticulation: Both automatic and volitional speech are equally affected by the same error patterns, showing that the difficulty lies in sound production rather than motor planning.
Physical Articulatory Behaviors
AOS: Visible groping movements occur as the person struggles to position their articulators (lips, tongue, jaw) correctly, often with multiple attempts and adjustments before producing a sound. This reflects the neurological difficulty in translating speech plans into precise movements.
Misarticulation: Oral movements appear normal and coordinated, without any visible struggle or groping. Errors occur despite proper physical ability to make the sounds.
Word Length Effect
AOS: Errors increase dramatically with longer, more complex words (e.g., "cat" may be clear while "catastrophe" becomes unintelligible) because the motor planning system becomes overloaded with more syllables to coordinate.
Misarticulation: Error patterns remain stable regardless of word length or complexity (e.g., substituting /w/ for /r/ occurs equally in simple words like "red" and complex words like "rectangle"), showing the issue is with individual sounds rather than motor planning.
Assessment
Oral Mechanism Examination
The structure and movement of oral structures are assessed.
Standardized Tests
Certain standardized tests are used to see what kinds of errors are present, whether they are consistent or inconsistent.
Speech Sampling
Speech samples are collected to see the severity of the type of errors, the severity of errors and whether they are consistent or inconsistent.
Treatment
The treatment options for AOS and misarticulation are different due to their different causes and symptoms. Both these conditions are mainly treated through speech therapy.
Therapy for AOS is mainly on retraining motor planning through intense repetition and multi-sensory cues.
Therapy for misarticulation is mainly focused on targeting specific sound errors through systematic practice and auditory training
The speech therapy techniques are:
Therapy for AOS
DTTC (Dynamic Temporal & Tactile Cueing)
Therapist and patient say words together simultaneously, then gradually transition to independent production. Here, main focus is on
Using hand gestures, touch cues, and exaggerated models
Starting with slow, exaggerated speech
Focusing on functional words (e.g., "hello," "hungry"
The reason why this can become effective is because it helps the system to build motor memory through lots of repetitions
PROMPT Therapy
In here, the therapist uses precise finger pressure on the face/jaw to guide proper mouth positions. This mainly focuses on:
Physical cues for sounds (e.g., tapping under chin for /k/)
Movement transitions between sounds.
This method has shown to be helpful for severe cases. It provides direct sensory feedback that is missing in AOS
Therapy for misarticulation
Traditional Articulation Therapy
The structure of progression is:
Sound in isolation (/s/)
Syllables (/si/, /sa/)
Words ("sun," "bus")
Phrases ("see the sun")
Sentences
Conversation
The tools used are:
Mirrors for visual feedback
Tongue depressors for placement
Diagrams of tongue positions
Minimal Pairs
This technique contrasts error vs the target sound. This helps in understanding the key difference and in practicing while focusing on the target sound.
Auditory Discrimination
Here, the following steps are done
The incorrect and correct sound production are identified
The particular target sound is focused in conversations
Recording and analyzing one’s own speech to improve awareness is also a major part of this therapy technique
Conclusion
Apraxia of speech and misarticulation represent two distinct categories of speech sound disorders with different underlying causes and treatment needs. Accurate diagnosis through comprehensive assessment is essential for developing effective intervention plans. While both conditions can significantly impact communication, appropriate therapy can lead to meaningful improvements in speech clarity and overall quality of life.
Understanding these differences helps ensure individuals receive the most appropriate care for their specific needs. With proper diagnosis, targeted intervention, and consistent practice, many people with either condition can achieve significant progress in their communication abilities.
To speak with a psychotherapist or one of the speech-language pathologists at Well Said: Toronto Speech Therapy, schedule an initial consultation by clicking the link below or calling (647) 795-5277.
