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When SLPs complete a speech sound evaluation with a client, there are many different moving pieces. One of them is to determine whether a speech sound disorder is present. Another is to determine what type of speech sound disorder a client may have. Identifying the type of speech sound disorder a client has is critical in deciding what type of treatment approach would be most effective for them.
Types of speech sound disorders
- Articulation: a motor issue is affecting the production of a specific sound or sounds (e.g. /s/, /l/, /r/, voiceless or voiced /th/)
- Phonological: a delay or disorder in the sound system of language is affecting the production of classes of sounds (e.g. final consonants, fricative sounds like /f, v, s, z, voiceless th, voiced th/, sounds made in the back of the mouth like /k, g, ng/, or pairs of consonants in blends)
- Motor speech: a disorder affecting the planning of motor movements for speech (e.g. apraxia of speech) or the execution of motor movements for speech (e.g. dysarthria)
- Structural: an impairment related to oral anatomical structural differences (e.g. cleft lip/palate) is affecting production of speech
- Sensory/perceptual: an impairment related to differences in the way sensory information is perceived (e.g. speech impairments due to hearing differences)
Below are some strategies that assist in determining what type of speech sound disorder is present during an evaluation:
Case History
Reviewing a client's case history can help identify relevant information for your speech evaluation. For example, you can check if they passed hearing screenings at the hospital or school during the initial family interview, if there's a family history of communication disorders or speech sound impairment, and if they've previously received services for other areas of concern. In the schools, if you have access to reports from other disciplines (e.g. audiology, psychoeducational reports, physical therapy, occupational therapy), these reports can offer additional insight into relevant medical diagnoses.
Assess speech at different levels of production
Speech sound production can happen in individual sounds, syllables, words, phrases, sentences, paragraphs, and in conversation. Many standardized speech assessments such as the Goldman-Fristoe Test of Articulation (GFTA) or the Arizona Articulation and Phonology Scale assess speech sounds in single words and also sounds in sentences. If a client can produce longer utterances, it's generally helpful to assess speech sounds at levels beyond just the single word level. Sentences, reading aloud (if the client is a reader), and conversational speech samples can help you identify errors and error patterns that are affecting overall speech intelligibility. Sometimes errors that aren't apparent in single words do show up when looking at sentences, reading aloud, or in conversation. This consideration is especially useful when you are re-evaluating a student who is receiving speech therapy services, as they may have worked on sounds in single words previously.
Articulation vs. phonology: Look at patterns in error productions
Are errors happening just in individual specific sounds, or are there error patterns that are affecting a broad range of sounds? Looking at the errors you obtain and identifying patterns will help you determine whether a client has an articulation impairment or a phonological impairment. You can use developmental norms to determine which errors are developmentally expected and which errors are not. It can also be useful to look at the types of errors you're observing. Distortion errors (e.g. an interdental, dentalized, or lateralized /s/, a distortion on /r/) are more often indicative of an articulation impairment. Deletion errors (e.g. of final consonants, or a sound in a blend) and errors across entire classes of sounds (e.g. fricatives, velar sounds like /k/ & /g/, liquid sounds like /l/ and /r/) are more often indicative of a phonological process. Sometimes clients can present with both articulation and phonological impairments.
Structural and motor speech: the importance of oral mechanism exams
Doing a thorough oral mechanism exam during a speech evaluation will often give you information to indicate whether structural or motor speech impairments are present. Observing articulators (e.g. lips, tongue, teeth, facial features) at rest and during movement can show you signs of weakness or asymmetries that might affect speech production. Teeth, dental alignment, and bite observations can be especially useful for identifying structural differences that could affect speech sounds such as /s/ and /z/. A modified tongue anchor, where a client protrudes their tongue while puffing their cheeks full of air, can be a quick way to screen for potential issues with airflow and resonance. If you have access to a flashlight or pen light, looking inside the client's mouth can help you identify potential structural differences such as a cleft palate.
Oral mech exams are also an opportunity to look at a client's motor speech skills. Prolonged phonation of /ah/ and alternating motion rates (rapidly repeating individual syllables /pa/, /ta/, and /ka/) can reveal issues with breath support, strength, speed, or coordination that could indicate a dysarthria. Sequential motion rates (rapidly repeating /pa-ta-ka/) or longer multisyllabic word repetition can reveal motor planning issues indicating an apraxia of speech. Observing a client's prosodic factors (e.g. volume, pitch, rate of speech) can also reveal useful information about their motor speech skills.
Key takeaways
Case histories, identifying patterns, and oral mechanism exams provide lots of useful information to differentiate what type of speech sound disorder is present. Many of the standardized assessment measures SLPs use and observations of a client's speech also give useful information in determining the severity of the disorder. Ultimately, these sources of information allow SLPs to diagnose speech sound disorders in clients.
References
American Speech-Language-Hearing Association. (n.d.) Speech Sound Disorders: Articulation and phonology. Retrieved December 29, 2025 from https://www.asha.org/practice-portal/clinical-topics/articulation-and-phonology
Ian Quillen M.S., CCC-SLP
Date
Share
When SLPs complete a speech sound evaluation with a client, there are many different moving pieces. One of them is to determine whether a speech sound disorder is present. Another is to determine what type of speech sound disorder a client may have. Identifying the type of speech sound disorder a client has is critical in deciding what type of treatment approach would be most effective for them.
Types of speech sound disorders
- Articulation: a motor issue is affecting the production of a specific sound or sounds (e.g. /s/, /l/, /r/, voiceless or voiced /th/)
- Phonological: a delay or disorder in the sound system of language is affecting the production of classes of sounds (e.g. final consonants, fricative sounds like /f, v, s, z, voiceless th, voiced th/, sounds made in the back of the mouth like /k, g, ng/, or pairs of consonants in blends)
- Motor speech: a disorder affecting the planning of motor movements for speech (e.g. apraxia of speech) or the execution of motor movements for speech (e.g. dysarthria)
- Structural: an impairment related to oral anatomical structural differences (e.g. cleft lip/palate) is affecting production of speech
- Sensory/perceptual: an impairment related to differences in the way sensory information is perceived (e.g. speech impairments due to hearing differences)
Below are some strategies that assist in determining what type of speech sound disorder is present during an evaluation:
Case History
Reviewing a client's case history can help identify relevant information for your speech evaluation. For example, you can check if they passed hearing screenings at the hospital or school during the initial family interview, if there's a family history of communication disorders or speech sound impairment, and if they've previously received services for other areas of concern. In the schools, if you have access to reports from other disciplines (e.g. audiology, psychoeducational reports, physical therapy, occupational therapy), these reports can offer additional insight into relevant medical diagnoses.
Assess speech at different levels of production
Speech sound production can happen in individual sounds, syllables, words, phrases, sentences, paragraphs, and in conversation. Many standardized speech assessments such as the Goldman-Fristoe Test of Articulation (GFTA) or the Arizona Articulation and Phonology Scale assess speech sounds in single words and also sounds in sentences. If a client can produce longer utterances, it's generally helpful to assess speech sounds at levels beyond just the single word level. Sentences, reading aloud (if the client is a reader), and conversational speech samples can help you identify errors and error patterns that are affecting overall speech intelligibility. Sometimes errors that aren't apparent in single words do show up when looking at sentences, reading aloud, or in conversation. This consideration is especially useful when you are re-evaluating a student who is receiving speech therapy services, as they may have worked on sounds in single words previously.
Articulation vs. phonology: Look at patterns in error productions
Are errors happening just in individual specific sounds, or are there error patterns that are affecting a broad range of sounds? Looking at the errors you obtain and identifying patterns will help you determine whether a client has an articulation impairment or a phonological impairment. You can use developmental norms to determine which errors are developmentally expected and which errors are not. It can also be useful to look at the types of errors you're observing. Distortion errors (e.g. an interdental, dentalized, or lateralized /s/, a distortion on /r/) are more often indicative of an articulation impairment. Deletion errors (e.g. of final consonants, or a sound in a blend) and errors across entire classes of sounds (e.g. fricatives, velar sounds like /k/ & /g/, liquid sounds like /l/ and /r/) are more often indicative of a phonological process. Sometimes clients can present with both articulation and phonological impairments.
Structural and motor speech: the importance of oral mechanism exams
Doing a thorough oral mechanism exam during a speech evaluation will often give you information to indicate whether structural or motor speech impairments are present. Observing articulators (e.g. lips, tongue, teeth, facial features) at rest and during movement can show you signs of weakness or asymmetries that might affect speech production. Teeth, dental alignment, and bite observations can be especially useful for identifying structural differences that could affect speech sounds such as /s/ and /z/. A modified tongue anchor, where a client protrudes their tongue while puffing their cheeks full of air, can be a quick way to screen for potential issues with airflow and resonance. If you have access to a flashlight or pen light, looking inside the client's mouth can help you identify potential structural differences such as a cleft palate.
Oral mech exams are also an opportunity to look at a client's motor speech skills. Prolonged phonation of /ah/ and alternating motion rates (rapidly repeating individual syllables /pa/, /ta/, and /ka/) can reveal issues with breath support, strength, speed, or coordination that could indicate a dysarthria. Sequential motion rates (rapidly repeating /pa-ta-ka/) or longer multisyllabic word repetition can reveal motor planning issues indicating an apraxia of speech. Observing a client's prosodic factors (e.g. volume, pitch, rate of speech) can also reveal useful information about their motor speech skills.
Key takeaways
Case histories, identifying patterns, and oral mechanism exams provide lots of useful information to differentiate what type of speech sound disorder is present. Many of the standardized assessment measures SLPs use and observations of a client's speech also give useful information in determining the severity of the disorder. Ultimately, these sources of information allow SLPs to diagnose speech sound disorders in clients.
References
American Speech-Language-Hearing Association. (n.d.) Speech Sound Disorders: Articulation and phonology. Retrieved December 29, 2025 from https://www.asha.org/practice-portal/clinical-topics/articulation-and-phonology
Ian Quillen M.S., CCC-SLP
