Tara McAllisterMontclair State University, Montclair,

New Jerseymcallistert@mail.montclair.edu

PATTERNS OF GESTURAL OVERLAP ACCOUNT FOR POSITIONAL FRICATIVE NEUTRALIZATION

IN CHILD PHONOLOGY

OutlineAn interesting data set from phonological

acquisition (positional fricative gliding).Why these child data are difficult to square with

what we know about adult phonological typology.Claim: A phonetically-based approach to phonology

makes it possible to give a principled account of child-specific phenomena.

Fricative substitution errors are analyzed as a phonologized response to a child-specific articulatory limitation on overlapping vowel and fricative gestures.

Positional asymmetry emerges as the consequence of differing degrees of gestural overlap permitted in syllable-initial versus syllable-final position (Articulatory Phonology).

Case study dataData were collected from a single case study

subject between the ages of 3;9 and 4;3.

‘Ben’ is a monolingual English learner with severe phonological delay/disorder.

Active phonological patterns in addition to the pattern of interest: cluster reductionvelar frontingliquid glidingfinal devoicingdebuccalization of coda stops

Positional neutralization of fricatives (PFN)Ben’s positional fricative neutralization pattern

(3;9-3;10): Syllable-initial fricatives are realized as glides.

[ji] see [jaʔ] shark [joĩ] sewing [jip]

sheep [jiba] zebra [wuʔ] food

[wodaʔ] forgot  

Positional neutralization of fricatives (PFN)Ben’s positional fricative neutralization pattern (3;9-

3;10): Syllable-initial fricatives are realized as glides.

[ji] see [jaʔ] shark [joĩ] sewing [jip] sheep [jiba] zebra [wuʔ] food

[wodaʔ] forgot  Syllable-final fricatives preserve faithful manner

(not necessarily place or voicing).[mas] mouse [jʊʃ] fish[bis] beans [bʌʃbaʔ]Spongebob[babajis] strawberries [was] five

Why is PFN of interest?Not unique to Ben.

Numerous studies have documented children acquiring fricatives in syllable-final before syllable-initial contexts.In babbling (Gildersleeve-Neumann et al. 2000; Oller & Eilers,

1982; Redford et al. 1997)

In meaningful speech (Dinnsen, 1996; Edwards, 1996; Farwell, 1976; Ferguson, 1978; Stites, Demuth, & Kirk, 2004; Stoel-Gammon, 1985)

Pattern is not universal, but general consensus is that fricatives in final position have a favored status in acquisition (Edwards, 1979).

Why is PFN of interest?PFN is a child-specific pattern that reverses a

strong bias in adult phonological typology.

In fully-developed phonologies, the maximum range of featural contrasts is realized in initial/prevocalic position.Example: Manner contrasts in Korean (Ahn, 1998)

Stop, fricative, affricate manner allowed in onset position.

All manner contrasts neutralized to stop in coda position.

PFN belongs to set of child processes of neutralization in strong position (Dinnsen & Farris-Trimble, 2008; Inkelas & Rose, 2003, 2008; McAllister, 2009)

Challenge notion of continuity of child and adult grammars.

Neutralization in strong positionLet’s try to model PFN with a general constraint

*FRICATIVES:In a positional faithfulness framework (Beckman, 1997), we

need a constraint enhancing faithfulness to weak/final position.IDENT-manner-weak >> *FRICATIVES >> IDENT-manner

In a positional markedness framework (Smith, 2000, 2002), we need a constraint limiting featural contrasts in strong position. * #FRICATIVES >> IDENT-manner >> *FRICATIVES

If IDENT-manner-weak or *#FRICATIVES are possible constraints, we should find examples of adult phonologies with featural neutralization in strong position.Such grammars are in fact unattested.

Phonetics in child phonologyThe challenge: Model children’s positional

neutralization without making incorrect predictions for the possible range of variation in adult grammars.

My claim: The most principled accounts of child-specific phonological patterns have adopted a phonetically-based approach to phonology (Dinnsen & Farris-Trimble, 2008; Inkelas & Rose, 2003, 2007; McAllister, 2009; Pater, 1997).

It is uncontroversial that children and adults experience the physical act of producing/perceiving speech in different ways.Different articulatory anatomy and speech-motor controlDifferent perceptual sensitivities

Phonetically-based phonologySince children and adults are subject to different

low-level phonetic pressures, the phonetically-based model predicts divergence in their grammars as well.

If a speaker experiences a major change at the phonetic level (e.g. articulatory maturation), the grammar can change in response to the new phonetic pressures. Accounts for elimination of child-specific phonological

phenomena in the course of typical maturation.

I will propose a formal phonological model of Ben’s PFN pattern with roots in a child-specific articulatory limitation.

Child-specific phonetic limitationsA phonetic difference between children and adults:

Children have difficulty moving the tongue independent of the jaw.Tongue is motorically complex, with many degrees of

movement freedom (Kent, 1992).

Control of the jaw, a bilaterally hinged joint, is motorically simple.

In early stages of motor maturation, tongue moves passively with the active jaw (MacNeilage & Davis, 1990).

Even after some capacity for independent tongue control is acquired, acoustic measurements reveal an ongoing preference for jaw-dominated gestures (Edwards, Fourakis, Beckman, & Fox, 1999)

Child-specific phonetic limitationsMy proposal: Preference for jaw-dominated

gestures takes on phonological status.

MOVE-AS-UNIT: ‘Avoid jaw-independent tongue gestures.’

MOVE-AS-UNIT can be analogized to effort-minimizing constraints in adult grammars.LAZY: ‘Minimize articulatory effort’ (Kirchner, 2001)

MINIMISEEFFORT (Flemming, 2001)

Difference is that MOVE-AS-UNIT responds to a type of movement that is effortful for children but not for adults.

Why are fricatives dispreferred?In adult speech, fricative-containing syllables

involve independent tongue and jaw control.In a fricative-vowel syllable, the jaw reaches its target

before the tongue tip. (Tongue remains high to sustain frication while jaw lowers in anticipation of the upcoming vowel.)

In a vowel-fricative syllable, the tongue tip reaches its target before the jaw (Mooshammer et al., 2006).

A speaker who moves tongue and jaw as one unit cannot achieve this coarticulation.A typical coarticulated fricative-vowel or vowel-

fricative transition will thus violate MOVE-AS-UNIT.

Stops and glides do not require differentiated control of tongue and jaw (Kent, 1992).

Why the positional asymmetry?Spectrograms of Ben’s output reveal an

asymmetry between initial and final fricatives: Syllable-initial fricatives make an immediate

transition into the following vowel.Syllable-final fricatives tend to be separated from

the vowel by silence and/or aspiration noise.

Pause separating vowel and coda fricative indicates that the gestures may not overlap at all.No MOVE-AS-UNIT violation.

Why the positional asymmetry?This pattern is not unique to Ben:

Target ‘nose’ produced by a typically developing child aged 2;11

Why the positional asymmetry?Target ‘kiss’ produced by a typically developing child aged

3;6

Non-overlapping vowel-fricative transitions can be observed in the speech of typically developing children.

How general is the phenomenon?Measured 237 vowel-fricative and fricative-vowel

transitions elicited from 17 TD children aged 2;11-5;7 (mean 4;7).Average duration of silence/aspiration noise separating a

vowel and a coda fricative was a substantial 88.4 ms. In 58.8% of tokens, this interval was ≥ 25% of total vocalic

interval (criterion for preaspiration adapted from Gordeeva & Scobbie, 2010).This is despite the fact that adult American English is

thought to lack preaspiration of fricatives (Turk, Nakai, & Sugahara, 2006).

There was no significant difference in the duration of silence/aspiration before a voiced versus a voiceless fricative.

Between an onset fricative and the following vowel, the mean duration of non-canonical frication noise was 20.4 ms.Only 4.1% met criterion for postaspiration.

Why the positional asymmetry?Conclusion: Child speakers produce fricative-

vowel transitions with a greater degree of overlap than vowel-fricative transitions.Lesser MOVE-AS-UNIT violation in the latter case.

However, evidence that fricatives and vowels do not always overlap in final position is insufficient to account for PFN. Necessary to explain why a comparable non-

overlapped transition is not available in syllable-initial position.

Constraints on gestural timingArticulatory Phonology: Gestures stand in

characteristic timing relations with respect to one another (Browman & Goldstein, 1986 et seq.).

Characteristic patterns of gestural overlap can be encoded in Optimality-Theoretic coordination constraints (Gafos, 2002).

CV-COORD: ALIGN(C, C-Center, V, Onset)VC-COORD: ALIGN(V, Release, C, Target)

Non-overlapping transitions violate CV-COORD/VC-COORDIf CV-COORD >> VC-COORD, non-overlapping gestures

will be penalized more heavily in initial relative to final position.

Onset

Release Target C-Center

Constraints on gestural timingExperimental evidence of syllable position effects

suggests that CV-COORD >> VC-COORD may be the default.

Degree of overlap between a vowel and a coda consonant varies with changes in rate or prosody, but onset-vowel transitions maintain stable timing across all conditions (Tuller & Kelso, 1990, 1991).

Nam et al. (2010): CV and VC transitions have different coupling modes and consequently different coupling strength.CV coupling is in-phase (synchronous), more stable. VC coupling is anti-phase (offset by 180˚), less stable.Accounts for developmental and typological primacy of

the CV syllable shape.

Modeling Ben’s grammarPFN will occur when CV-COORD >> FAITH >> VC-

COORD.Harmonic Grammar framework turns out to be

the best fit for the data, but here classic OT is used for simplicity.

Table 1. An initial fricative is replaced with a glide. /sɔ/, ‘saw’

IDENT-

Continuant MOVE-AS-

UNIT CV-COORD

IDENT-

Consonantal VC-COORD

a. s ɔ

*!

b. s ɔ

*!

c. j ɔ

*

Modeling Ben’s grammarTable 2. A final fricative preserves faithful manner.

/ʌs/, ‘us’ MOVE-AS-

UNIT CV-COORD

IDENT-

Consonantal VC-COORD

a. ʌ s

*!

b. ʌ s

*

c. ʌ j

*!

More evidence for the gestural accountBefore acquiring faithful fricatives in all contexts,

Ben went through an intermediate stage (3;11-4;2) in which initial fricatives were realized with an epenthetic glide:

[sjɔ] saw [sjak] sock[sjaʊt] salt [sjaoʊ] share[sjoʊ] sew [ʃjaoʊ] shell

Epenthesis is a truly unexpected repair because Ben’s phonology at the time lacked initial consonant clusters, including obstruent-glide clusters.

[dɑk]clock[bun] spoon[bɑ:t] bread [dʊsɛn]question

More evidence for the gestural accountArticulatory Phonology literature reveals several cases

where apparent epenthetic segments are the perceptual consequence of non-overlapping gestural coordination.Perceived epenthetic schwa in coda clusters in Moroccan

Colloquial Arabic (Gafos, 2002).

Perceived epenthetic schwa in English speakers’ attempted non-native clusters (Davidson, 2003).

Vocal tract is briefly open during non-overlapped transition; sound produced is perceived as an epenthetic segment.

Transition from a vowel to a coda fricative has come to feature a palatal glide in some fully-developed phonologies, e.g. luz, ‘light’ [lujs] in certain dialects of Brazilian Portuguese (Albano, 1999; Operstein, 2010).

More evidence for the gestural accountIf IDENT-Consonantal is promoted above CV-

COORD, the optimal candidate will feature a non-overlapped fricative-vowel transition instead of glide substitution./sɔ/, ‘saw’ *COMPLEX

MOVE-AS-UNIT

IDENT-

Consonantal CV-COORD VC-COORD

a. s ɔ

*!

b. j ɔ

*!

c. s j ɔ

*

d. s j ɔ

* *

More evidence for the gestural accountSo why don’t we hear a transitional glide in Ben’s final

vowel-fricative transitions?Visual inspection of coda fricatives shows cessation of

voicing before onset of frication.Preaspiration obscures formant transitions that would

create percept of epenthetic glide.

Finding that glottal opening occurs in advance of the oral constriction for a fricative coda is entirely consistent with the gestural coordination analysis pursued here.Syllable position effects affecting timing of gestures within

a compound segment (e.g. nasal, voiceless obstruent).In initial position, both gestures are roughly synchronous.In final position, glottal opening gesture tends to precede

the oral constriction (Krakow, 1999).

ConclusionsPFN is difficult to model without creating incorrect

predictions for the range of variation in adult typology.

Roots in children’s articulatory limitations can account for absence of pattern from adult grammars.

Positional nature of fricative neutralization follows from the fact that inter-gestural timing is more tightly constrained in CV than VC contexts.

Provides new evidence that patterns of inter-gestural coordination previously described in adult speakers are also influential in developmental phonology.

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