Speech Sound Disorders: A Lifespan Evidence-Based Perspective
Introduction to Speech Sound Disorders
- Definition: Speech sound disorders (SSDs) in children refer to difficulties related to:
- How speech sounds are used in the language (phonology).
- How sounds of the language are produced (articulation).
- Causes of Speech Sound Disorders:
- Impairments in the phonological representation of speech sounds.
- Inability or difficulty perceiving speech sounds.
- Structural abnormalities affecting the integrity of the speech production mechanism.
- Motor speech disorders, such as dysarthria and childhood apraxia of speech (CAS).
- Severity: SSDs can range in severity.
- Two Critical Skill Areas:
- Articulation: The ability to move the articulators (tongue, lips, velum) and coordinate the speech production systems.
- Phonology: Understanding sounds and how they are combined to make words; having an organized sound system.
Understanding Speech Sounds
- Phonemes: Spoken English has approximately 40 different phonemes, which combine to form words, phrases, and sentences.
- This is distinct from the 26 letters of the alphabet.
- Some phonemes are universal, while others are language-specific.
- Phonotactic Rules: These rules specify acceptable sequences and locations of phonemes within a language.
- International Phonetic Alphabet (IPA):
- A special alphabet used to represent phonemes (sounds), not the orthographic representation (letters of the alphabet used for reading and writing).
Classification of Speech Sounds
- Phonemes are categorized as either vowels or consonants.
- Vowels:
- Produced with a relatively open or unobstructed vocal tract.
- Described according to tongue and lip position and the relative degree of tension in the articulators.
- Consonants:
- Made with some degree of constriction in the vocal tract.
- Classified by place of articulation, manner of production, and voicing.
Classification of Consonants by Place, Manner, and Voicing
- Manner of Production: Refers to the degree of constriction somewhere along the vocal tract.
- Types include: Stop consonants, fricatives, affricates, nasals, glides, liquids (refer to textbook pages 143/144).
- Place of Articulation: The point of closure or constriction in the vocal tract.
- Types include: Bilabial, labiodental, interdental/linguadental, alveolar, palatal, velar, glottal (refer to textbook pages 143/144).
- Voicing: Refers to the activity of the vocal folds during consonant sound production.
- Consonants are either voiced (vocal folds vibrate) or voiceless (vocal folds do not vibrate) (refer to textbook pages 143/144).
- Cognate Pairs: Consonants that share the same place and manner of articulation but differ only in voicing (e.g., /p/ (voiceless bilabial stop) and /b/ (voiced bilabial stop)).
- Consonant Classification Examples:
- /k/: Place: Velar. Manner: Stop. Voice: Voiceless.
- /m/: Place: Bilabial. Manner: Nasal. Voice: Voiced.
Classification of Vowels by Tongue and Lip Position and Tension
- Vowel Production: Sound energy from vibrating vocal folds is modified and resonated by the open vocal tract.
- Description Parameters:
- Part of tongue elevated: Front, center, back.
- Tongue height: High, mid, low.
- Amount of tension: Tense or lax.
- Lip position: Lip rounding or retraction also affects the vowel sound.
- Diphthongs: Occur when two vowels are produced in close proximity, creating a single, gliding sound (e.g., /aɪ/ as in
