Speech Sound Disorders-Articulation and Phonology

See the Assessment section of the Speech Sound Disorders Evidence Map for pertinent scientific evidence, expert opinion, and client/caregiver perspective.


Screening is conducted whenever a speech sound disorder is suspected or as part of a comprehensive speech and language evaluation for a child with communication concerns. The purpose of the screening is to identify those who require further speech-language/communication assessment or referral to other professional services.

Screening typically includes

  • formal screening measures that have normative data and/or cutoff scores,
  • informal measures, such as those designed by the clinician and tailored to the population being screened (e.g., for older students, screening procedures might include reading sentences and/or passages containing speech sounds to be assessed or obtaining a conversational speech sample),
  • comprehension and production of spoken and written language (as age-appropriate),
  • hearing screening to rule out hearing loss as a possible contributing factor to speech difficulties,
  • screening of oral motor functioning,
  • orofacial exam to identify structural bases for speech sound disorders (e.g., submucous cleft palate, malocclusion, ankyloglossia) and to assess facial symmetry.

Screening may result in

  • suggestions to encourage normal speech sound development and the prevention of speech-language impairment;
  • plans to monitor speech and language development;
  • referral for multi-tier system of supports such as response to intervention (RTI) services when appropriate;
  • referral for further speech and language assessment, including
    • a comprehensive speech sound assessment, if the child's speech sound system is not appropriate for his/her age and/or linguistic community,
    • a comprehensive language assessment,
    • a complete audiologic assessment,
    • a comprehensive oral motor/oral musculature assessment;
  • referral for medical or other professional services.

Comprehensive Assessment

Individuals suspected of having a speech sound disorder based on screening results are referred to an SLP for a comprehensive assessment. The assessment protocol may include an evaluation of language and literacy skills, if indicated, and takes into account cultural and linguistic speech differences across communities, including

  • current research and best practice in the assessment of speech sound disorders in the language(s) and/or dialect(s) used by the client;
  • phonemic and allophonic variations of the language(s) and/or dialect(s) used in the community and how those variations affect a determination of a disorder or a difference;
  • differences among speech sound disorders, accents, dialects, patterns of transfer from one language to another, and typical developmental patterns. See phonemic inventories across languages.

Comprehensive assessment for speech sound disorders typically includes

  • case history;
  • oral mechanism examination;
  • hearing screening;
  • speech sound assessment (single-word testing and connected speech sampling), including
    • severity,
    • intelligibility,
    • stimulability,
    • speech perception;
  • spoken-language testing, including
    • receptive and expressive language assessment,
    • phonological processing;
  • literacy assessment.

It is not appropriate to determine a standard score for any assessment that is not normed on a group representative of the individual being assessed.

Assessment may result in

  • diagnosis of a speech sound disorder,
  • description of the characteristics and severity of the disorder,
  • recommendations for intervention targets,
  • identification of factors that might contribute to the speech sound disorder,
  • diagnosis of a spoken language (listening and speaking) disorder,
  • identification of literacy problems,
  • monitoring of literacy learning progress in students with identified speech sound disorders by SLPs and other professionals in the school setting,
  • recommendations for response to intervention (RTI) services in the schools to support speech and language development,
  • referral to other professionals as needed.

Case History

The case history typically includes gathering information about

  • family's concerns about the child's speech;
  • history of middle ear infections;
  • history of speech, language, and/or literacy difficulties in the family;
  • languages used in the home;
  • primary language spoken by the child;
  • teacher's perception of the child's intelligibility and participation in the school setting and how the child's speech compares with that of peers in the classroom;
  • family's and other communication partners' perception of intelligibility.

See cultural competence for guidance on taking a case history with all clients.

Oral Mechanism Examination

The oral mechanism examination evaluates the structure and function of the speech mechanism to assess whether the system is adequate for speech production.  This examination typically includes assessment of

  • occlusion and specific tooth deviations;
  • hard and soft palate (clefts, fistulas, bifid uvula);
  • function (strength and range of motion) of the lips, jaw, tongue, and velum;
  • placement of the tongue at rest and during speech to rule out tongue thrust, an oral myofunctional phenomenon, that can affect production of some sounds (e.g., /s/,/z/, "sh", "zh", "ch" and "j").

Hearing Screening

If not completed during the speech sound screening, a hearing screening is conducted during the comprehensive speech sound assessment. The screening typically includes

  • otoscopic inspection of the ear canal and tympanic membrane,
  • puretone audiometry,
  • immittance testing to assess middle ear function.

Speech Sound Assessment

The acquisition of speech sounds is a developmental process, and children often demonstrate "typical" errors and phonological patterns during this acquisition period. For example, it is considered typical and acceptable for younger children to replace later-acquired sounds, such as /s/, with earlier-acquired sounds, such as /t/, up until a certain age range. Developmentally appropriate errors and patterns are taken into consideration during assessment for speech sound disorders in order to differentiate typical errors from those that are unusual or not age-appropriate. The speech sound assessment typically employs both standardized assessment instruments and a variety of sampling procedures.

Single-Word Testing—provides identifiable units of production and allows all sounds in the language to be elicited in a number of contexts; however, it may or may not accurately reflect production of the same sounds in connected speech.

Connected Speech Sampling—provides information about production of sounds in connected speech using a variety of talking tasks (e.g., storytelling or retelling, describing pictures, normal conversation about a topic of interest) and communication partners (e.g., peers, siblings, parents, clinician).

Assessment procedures typically evaluate the child's speech sound system, including

  • sounds, sound combinations, and syllable shapes produced accurately, including
    • sounds in various word positions (e.g., initial, within word, and final word position) and in different phonetic contexts,
    • phoneme sequences (e.g., vowel combinations, consonant clusters, and blends),
    • syllable shapes (e.g., simple CV to complex CCVCC);
  • speech sound errors, including
    • error type(s) (e.g., deletions, omissions, substitutions, distortions, additions),
    • error distribution (e.g., position of sound in word),
    • articulation errors—relatively consistent errors, with preserved phonemic contrasts (e.g., /l/ and /r/ are consistently distorted, but clearly different from one another; Bauman-Waengler, 2012;
  • error patterns (i.e., phonological patterns)—systematic sound changes or simplifications that affect a class of sounds (e.g., fricatives), sequences of sounds (e.g., consonant clusters), or syllable structures (e.g., complex syllable structures or multisyllabic words.

See phonological processes (patterns) and age of customary consonant production [PDF].


Severity is a qualitative judgment made by the clinician that indicates the significance of the speech sound disorder on the child's communication functioning in daily activities. It is typically defined along a continuum from mild to severe or profound. There is no clear consensus regarding the best way to determine the severity of a speech sound disorder.

A numerical scale or continuum of disability is often used, because it is time-efficient and because of the lack of more definitive ways to make this determination. Prezas and Hodson (2010) utilize a continuum from mild (omissions are rare; few substitutions) to profound (extensive omissions and many substitutions; extremely limited phonemic and phonotactic repertoires), with distortions and assimilations occurring in varying degrees at all levels of the continuum.

Shriberg and Kwiatkowski (1982a, 1982b) proposed a quantitative approach in which the percentage of consonants correct (PCC) is used to determine severity on a continuum from mild to severe. This type of calculation most closely aligns with the listener's perceptions of severity. For example, a PCC of 85-100 is considered "mild," while a PCC of less than 50 is considered "severe." This approach has been modified to include a total of 10 such indices, including percent vowels correct (PVC; Shriberg, Austin, Lewis, McSweeny, & Wilson, 1997).


Intelligibility is a subjective, perceptual judgment, based on how much of the child's spontaneous speech is understood by the listener. Intelligibility can range from "intelligible" (message is completely understood) to "unintelligible" (message is not understood). Intelligibility is a factor that is frequently used when judging the severity of the child's speech problem (Kent, Miolo, & Bloedel, 1994). It is often used to determine the need for intervention and to evaluate progress in therapy. A child of 3 years-of-age or older who is unintelligible is generally recognized as a candidate for treatment (Bernthal, Bankson, & Flipsen, 2013).

A guideline for expected conversational intelligibility levels of typically developing children talking to unfamiliar listeners can be calculated by dividing the child's age in years by four and converting that number into a percentage (Coplan & Gleason, 1988; Flipsen, 2006):

  • 1 year—25% intelligible,
  • 2 years—50% intelligible,
  • 3 years—75% intelligible,
  • 4 years—100% intelligible.

Although the degree of speech intelligibility is a subjective, perceptual judgment, a number of quantitative measures have been proposed, including calculating the percentage of words understood in the speech sample (Bauman-Waengler, 2012; McLeod, Harrison, & McCormack, 2012). There is no single intelligibility assessment procedure that is appropriate for all children across settings, and intelligibility may vary depending on the setting. Several factors can influence the intelligibility of speech, including

  • level of communication (e.g., single words vs. conversation);
  • listener's familiarity with the speaker's speech pattern;
  • speaker's rate, inflection, stress patterns, pauses, voice quality, loudness, and fluency;
  • social environment (e.g., familiar vs. unfamiliar conversational partners, one-on-one vs. group conversation);
  • communication cues for listener (e.g., known vs. unknown context);
  • signal-to-noise ratio (e.g., amount of background noise);
  • listener's skill.

Stimulability testing examines the child's ability to produce or imitate a misarticulated sound correctly when a model is provided by the clinician. It provides information about how well the individual imitates the sound in one or more contexts (e.g., isolation, syllable, word, phrase) and helps determine the level of cueing necessary to achieve the best production (e.g., auditory model; auditory and visual model; auditory, visual, and verbal model; tactile cues). There are few standardized procedures for testing stimulability (Glaspey & Stoel-Gammon, 2007; Powell & Miccio, 1996), although some test batteries include stimulability subtests.

Stimulability testing is used to

  • determine if the sound(s) are likely to be acquired without intervention,
  • select appropriate therapy targets,
  • predict improvement in therapy.
Speech Perception Testing

Speech perception testing is used to determine if a child is able to perceive the difference between the standard production of a sound and his/her own error production. It may be indicated for children who do not use phonemic contrasts to in order to determine if errors are related to a generalized perceptual problem resulting in an inability to differentiate various minimal pair sound contrasts (Bernthal et al., 2013).

A number of different test paradigms are used to assess speech sound discrimination, including

Auditory Discrimination—syllable pairs containing a single phoneme contrast are presented, and the child is instructed to say "same" if the paired items sound the same and "different" if they sound different.

Picture Identification—the child is shown 2-4 pictures representing words with minimal phonetic differences. The clinician says one of these words, and the child is asked to point to the correct picture.

Pronunciation Accuracy/Inaccuracy,

  • Speech production–perception task—using sounds the child is suspected of having difficulty perceiving, picture targets containing these cards are used as visual cues, and the child is asked to judge whether the speaker says the item correctly (e.g., picture of a ship is shown; speaker says, "ship" or "sip"; Locke, 1980).
  • Mispronunication detection task—using computer-presented picture stimuli and recorded stimulus names (either correct or with a single phoneme error), the child is asked to detect mispronunciations by pointing to a green tick for "correct" or a red cross for "incorrect" (McNeill & Hesketh, 2010).
  • Lexical decision/judgment task—multiple speakers are used to assess the child's ability to identify words that are pronounced correctly vs. incorrectly; the targeted contrasting phoneme is used. For example, the child points to the picture of the targeted word "lake" and points to an" X" if the word on the picture was articulated incorrectly (e.g., "wake"; Rvachew, Nowak, & Cloutier, 2004).
Special Considerations: Assessing Young, Unintelligible and/or Reluctant Children

Young children might not be able to follow directions for standardized tests, might have limited expressive vocabulary, and might produce words that are unintelligible. Other children, regardless of age, may produce less intelligible speech or be reluctant to speak in an assessment setting. Strategies for collecting an adequate speech sample with these populations include

  • obtaining a speech sample during the assessment session using play activities,
  • involving parents/caregivers in the session to encourage talking,
  • asking parents/caregivers to supplement data from the assessment session by recording the child's speech at home during spontaneous conversation,
  • asking parents/caregivers to keep a log of the child's intended words and how these are pronounced.

Sometimes, the speech sound disorder is so severe that the child's intended message cannot be understood. However, even when a child's speech is unintelligible, it is usually possible to obtain information about his/her speech sound production. For example

  • a single-word articulation test provides opportunities for production of identifiable units of sound, and these productions can usually be transcribed;
  • it may be possible to understand and transcribe a spontaneous speech sample by using a structured situation to provide context when obtaining the sample, annotating the recorded sample by repeating the child's utterances, when possible, to facilitate later transcription.
Special Considerations: Bilingual/Multilingual Populations

Assessment of a bilingual individual requires an understanding of both linguistic systems, because the sound system of one language can influence the sound system of another language. The assessment process must identify whether differences are truly related to a speech sound disorder or are normal variations of speech caused by the first language.

When assessing a bilingual or multilingual individual, clinicians typically

  • gather information, including
    • language history and language use to determine which language(s) should be assessed;
    • phonemic inventory, phonological structure, and syllable structure of the non-English language;
    • dialect of the individual;
  • assess phonological skills in both languages in single words as well as in connected speech;
  • determine if difficulty in distinguishing phonemes in English is due to the presence of these sounds as allophones in the child's primary language;
  • account for dialectal differences;
  • identify and assess the child's
    • common substitution patterns (those seen in typically developing children),
    • uncommon substitution patterns (those often seen in individuals with a speech sound disorder),
    • cross linguistic effects (the phonological system of one's native language influencing the production of sounds in English, resulting in an accent—phonetic traits from a person's original language (L1) that are carried over to a second language (L2; Fabiano-Smith & Goldstein, 2010).

See phonemic inventories across languages and bilingual service delivery.

Spoken Language Testing

Language testing is included in a comprehensive speech sound assessment because of the high incidence of co-occurring language problems in children with speech sound disorders (Shriberg & Austin, 1998). Typically, the assessment begins with a screening of receptive language and expressive language. A full language battery is performed if indicated by screening results.

Phonological Processing

Phonological processing is the use of the sounds of one's language (i.e., phonemes) to process spoken and written language (Wagner & Torgesen, 1987).The broad category of phonological processing includes phonological awareness, phonological working memory, and phonological retrieval.

Phonological Awareness—the awareness of the sound structure of a language and the ability to consciously analyze and manipulate this structure via a range of tasks, such as speech sound segmentation and blending at the word, onset-rime, syllable, and phonemic levels.

Phonological Working Memory—involves storing phoneme information in a temporary, short-term memory store (Wagner & Torgesen, 1987). This phonemic information is then readily available for manipulation during phonological awareness tasks. Nonword repetition (e.g., repeat /pæg/) is one example of a phonological working memory task.

Phonological Retrieval—the ability to recall the phonemes associated with specific graphemes, which can be assessed by rapid naming tasks (e.g., rapid naming of letters and numbers). This ability to recall the speech sounds in one's language is also integral to phonological awareness.

All three components of phonological processing are important for speech production as well as the development of spoken and written language skills. It is important to screen phonological processing skills to determine if they should be included in the comprehensive speech sound disorder assessment. In addition, it is necessary to monitor the spoken and written language development of children with phonological processing difficulties.

Literacy Assessment [Reading and Writing]

Difficulties with the speech processing system (e.g., listening, discriminating speech sounds, remembering speech sounds, producing speech sounds) can lead to both speech production and phonological awareness difficulties that can hamper the development of literacy (Anthony et al., 2011; Leitão & Fletcher, 2004; Lewis et al., 2011). Children who perform well on sound awareness tasks become successful readers and writers, while children who struggle with such tasks often do not. In their "critical age" hypothesis, Bishop and Adams (1990) state that children who are not intelligible by 5½ years of age will likely have difficulties with decoding and spelling.

For typically developing children, speech production and phonological awareness develop in a mutually supportive way (Carroll, Snowling, Stevenson, & Hulme, 2003; National Institute for Literacy, 2009). As children playfully engage in sound play, they eventually learn to segment words into separate sounds and "map" sounds onto printed letters.

The understanding that sounds are represented by symbolic code (e.g., letters and letter combinations) is essential for reading and spelling. For reading, children have to be able to segment a written word into individual sounds, based on their knowledge of the code, and then blend those sounds together to form a word. When spelling, they have to be able to segment a spoken word into individual sounds and then choose the correct code to represent these sounds (National Institute of Child Health and Human Development, 2000; Pascoe, Stackhouse & Wells, 2006).

Components of the literacy assessment include the following, depending on the child's age and expected stage of literacy development.

Print Awareness—recognizing that books have a front and back and that the direction of words is from left to right and recognizing where words on the page start and stop.

Alphabet Knowledge—including naming/printing alphabetic letters from A to Z.

Sound-Symbol Correspondence—knowing that letters have sounds and knowing the sounds for corresponding letters and letter combinations.

Reading Decoding—using sound-symbol knowledge to segment and blend sounds in grade-level words.

Spelling—using sound-symbol knowledge to spell grade-level words.

Reading Fluency—reading smoothly without frequent or significant pausing.

Reading Comprehension—understanding grade-level text, including the ability to make inferences.  

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