Complexity approaches

How do complexity approaches differ from other approaches?

By how treatment targets are selected

• Analyse children's phonological system to determine what they know and what they need to know

Complexity concept

Treating more complex sounds exposes children to complex aspects of the phonological system and results in greater generalisation to untreated related targets

• acquisition of more complex features may generalise to less complex features

• By prioritising a complex target for intervention, can help child learn a lot more about the phonological system more efficiently

Candidates

• Children with phonological impairment

• Moderate to severe impairment

• 6+ sounds in error across 3 manner classes

• Research has involved 3-8 year old children

Productive Phonological Knowledge (PPK)

• how much child "knows" about producing a specific sound

• 6 levels ranging from most knowledge (100% accurate in all position) to least knowledge (not in inventory at all)

• Sound with least PPK considered more complex

• Sounds ranked according to how "marked" they are

Natural/un-marked sounds

• Typically considered easier to produce

• Occur more frequently in languages of the world

• E.g. vowels, glides, nasals and stops

Marked sounds

• Considered more difficult to produce

• Occur less frequently in languages of the world

• E.g. fricatives, affricates and liquids

Implicational Hierarchy (implied universals)

• Presence of one marked sound implies presence of other less marked sounds

• E.g. fricatives imply stops, voiceless stops imply voiced stops, closed syllables imply open syllables, consonant clusters imply singleton consonants

Implication hierarchy clinical application

Teaching sounds higher in hierarchy (more marked/complex) may facilitate acquisition of less marked sounds without direct intervention of those sounds

Sonority

Speech segments ranked according to amount of sonority (acoustic measure of amount of resonance in vocal cavity) used to produce sound

Sonority sequencing principle

 0. Vowels - most sonorous

1. Glides

2. Liquids

3. Nasals

4. Voiced fricatives

5. Voiceless fricatives

6. Voiced stops

7. Voiceless stops - least sonorous

• Syllables organised with least sonorous elements at margins and most sonorous elements in the middle

• E.g. plant = 7 > 2 > 0 < 3 < 7

• Consonant clusters with small sonority different between elements (e.g. /fl/) thought to be more marked/complex than those with larger sonority differences (e.g. /tw/)

Maximal oppositions

• Pair target sound with another known sound that is maximally different (differs in all features (P,V & M), including sonority)

• e.g. key and me

• For greater learning and generalisability

Empty set

• Pair target sound with another unknown sound that is maximally different (differs in all features, including sonority)

• E.g. key vs leigh/gee or fast vs last

What would treatment look like?

• 8 nonsense word pairs - to facilitate learning early on in intervention

• Each word assigned object name or character name via stories

• Imitation until 75% accuracy over 2 consecutive sessions for 7 sessions total

• Move to spontaneous production until 90% accuracy over 3 sessions or an additional 12 sessions

• 50% accuracy in conversation, then discontinue

• Check within and across class generalisation

• Check for expected generalisation based on implicational relationships