Speech Sound Disorders: Classification, Assessment, and Intervention

Speech Sound Disorder (SSD)

An impairment of an individual's sound system resulting in a significant problem with speech-sound production that differs from age- and culturally-based expectations.

Functional Speech Sound Disorder

A speech sound disorder of unknown origin, which includes articulation disorders and phonological disorders.

Organic Speech Sound Disorder

A speech sound disorder of known origin, such as a structural deficit, sensory impairment, or neurological impairment resulting in a motor speech disorder.

Articulation Disorder

An inability to articulate certain speech sounds correctly, often characterized by distortions or sound substitutions that do not result in phonemic or meaning differences.

Phonological Disorder

A speech sound disorder characterized by predictable, rule-based errors (such as fronting, stopping, and final consonant deletion) that affect more than one sound across a child's sound system.

Childhood Apraxia of Speech (CAS)

A neurological childhood speech sound disorder affecting the precision, coordination, and consistency of movements for speech production and prosody in the absence of other neuromuscular deficits.

Speech Variation

Speech differences stemming from a dialect or foreign accent that do not represent a speech disorder.

Dialect

A speech and language variation associated with a particular geographic region; not considered a speech disorder.

Accent

The pronunciation of a language in which phonetic characteristics are carried over from one language into another; not considered a speech disorder.

Phoneme

A speech sound capable of signaling a contrast in meaning between two words in a language, which holds no standalone meaning.

Coarticulation

The way sounds overlap during articulation, causing the articulatory characteristics of phonemes to vary according to their phonetic context.

Assimilation

The process by which the articulatory features of one sound take on the features of neighboring sounds within a word.

International Phonetic Alphabet (IPA)

A phonetic alphabet that describes and classifies each speech sound based on how and where it is produced in the speech mechanism.

Place of Production

The specific anatomical location within the vocal tract where a consonant sound is produced.

Manner of Production

The classification describing how the airstream is obstructed or modified as a speech sound is produced.

Voicing

A feature describing whether or not a speech sound is produced with vocal fold vibration.

Bilabial

A consonant place of production produced by bringing both lips together (e.g., /p/, /b/, /m/, /w/).

Labiodental

A consonant place of production formed by contact between the upper teeth and the lower lip (e.g., /f/, /v/).

Lingudental

A consonant place of production formed by placing the tongue between the upper and lower teeth.

Alveolar

A consonant place of production formed by elevating the tongue tip to the alveolar ridge (e.g., /t/, /d/, /s/, /z/, /n/).

Palatal

A consonant place of production formed by the tongue approximating or touching the region of the hard palate (e.g., /sh/, /ch/, /dg/, /j/, /r/).

Velar

A consonant place of production formed by the tongue contacting the region of the soft palate or velum (e.g., /k/, /g/, /ng/).

Glottal

A consonant place of production formed at the level of the glottis (e.g., /h/ or the glottal stop).

Stop

A consonant manner of production characterized by complete obstruction of airflow in the vocal tract followed by a sudden release.

Fricative

A consonant manner of production characterized by narrow constriction or partial obstruction of the vocal tract creating audible turbulence.

Affricate

A consonant manner of production that begins with a brief complete obstruction of the vocal tract followed by a gradual release of the airstream.

Nasal

A consonant manner of production produced with an open velopharyngeal port, directing airflow and acoustic resonance through the nasal cavity.

Liquid

A consonant manner of production produced with a relatively open vocal tract that is only slightly more restricted than for vowels (e.g., lateral /l/ and rhotic /r/).

Glide

A consonant manner of production characterized by a continuous gliding movement of the tongue toward or away from a vowel (e.g., /w/, /j/).

Fronting

A phonological substitution process in which a velar sound produced in the back of the mouth is replaced by an anterior sound made in the front (e.g., alveolar); typically eliminated by age 4.

Stopping

A phonological substitution process in which a fricative and/or affricate is replaced by a stop sound.

Gliding

A phonological substitution process in which a liquid consonant (/r/, /l/) is replaced by a glide (/w/, /j/); typically eliminated by age 6–7.

Deaffrication

A phonological substitution process in which an affricate sound is replaced with a fricative; typically eliminated by age 4.

Velar Assimilation

A phonological assimilation process where a non-velar sound changes to a velar sound due to the presence of a neighboring velar sound (e.g., 'kack' for 'tack'); typically eliminated by age 3.

Nasal Assimilation

A phonological assimilation process where a non-nasal sound changes to a nasal sound due to the presence of a neighboring nasal sound (e.g., 'money' for 'funny'); typically eliminated by age 3.

Cluster Reduction

A syllable structure process in which a consonant cluster is simplified into a single consonant; typically eliminated by age 4 (without /s/) or age 5 (with /s/).

Weak Syllable Deletion

A syllable structure process in which an unstressed or weak syllable in a word is omitted; typically eliminated by age 4.

Final Consonant Deletion

A syllable structure process involving the deletion of the final consonant of a word; typically eliminated by age 3.

Oral Mechanism Screening

A careful examination of the anatomical structures and motor functioning of the speech mechanism, including the lips, tongue, teeth, hard palate, and soft palate.

Ankyloglossia

A structural condition involving a short lingual frenum, commonly referred to as 'tongue-tie'.

Bifid Uvula

A cleft or split uvula identified during an oral mechanism screening that may be indicative of an underlying submucous cleft palate.

Phonological Awareness

The explicit awareness of and ability to manipulate the phonological sound units that make up words and non-words.

Stimulability

The ability