Development of coarticulatory patterns in spontaneous speech Melinda Fricke Keith Johnson University of California, Berkeley

Why study spontaneous speech? Laboratory speech is not always natural… – articulatory differences – psycholinguistic/plannin g differences (Zharkova, Hewlett, & Hardcastle, 2011)

Why study coarticulation? Coarticulation reveals speech planning. – articulatory planning, motor control – psycholinguistic planning, higher level processes (Zharkova, Hewlett, & Hardcastle, 2011)

What is coarticulation? Coarticulation: when an articulatory target affects adjacent targets. Anticipatory: [s] in “seat” vs. [s] in “suit” Perseverative: [s] in “geese” vs. [s] in “goose”

Research questions Can we use acoustic measures to detect fricative- vowel coarticulation in a corpus of spontaneous speech? If so… which ones? differences between anticipatory and perseverative coarticulation? differences between adult and child articulatory patterns?

The Corpora Buckeye Corpus of Conversational Speech (Pitt et al., 2007) – 40 adults (20 men/women), ~ 1 hour each – sociolinguistic interviews Davis Corpus, CHILDES Database (Davis et al., 2002; MacWhinney, 2000) – 21 children, ~ 1 hour/week – spontaneous interactions with caregivers

Adult data total # of tokens = 3794 front [i, ɪ, e, ɛ]round[u, ʊ, o] anticipatory 1362[si]1535 [su] perseverative 618[is]279[us] TOTAL

Child data 11 children (5 boys) produced tokens of [s] in identifiable words age range: 1;1 – 3;1 total # tokens = 3035 total # unique words = 425 – “this” (630), “yes” (179) – “juice” (139), “house” (53), “nose” (33) front [i, ɪ, e, ɛ]round[u, ʊ, o] anticipatory 615 [si] 103 [su] perseverative 1801 [is] 516 [us] TOTAL

Child data Token Contributions by Child age in months each color = 1 child

Fricative measurements adult spectra 0 – 8 kHz child spectra 0 – 11 kHz all fricatives hand labeled measurements taken at 4 locations – 40 ms Hamming window centered at 20%, 50%, 80% duration of fricative 20 ms into vowel today: high frequency centroid, amplitude ratio, kurtosis

High frequency centroid Inversely correlated with length of front cavity. low value = longer front cavity = rounding + PoA Weighted mean frequency above… – 2125 Hz (men) – 2500 Hz (women) – 3500 Hz (children) (McGowan & Nittrouer, 1988; Li, Edwards, & Beckman, 2007)

Statistical modeling Linear mixed effects regression – random effects speaker, word (for child data only) – fixed effects measurement location (20% vs. 80%) context (round vs. non-round vowel) interaction term Separate models for adults vs. children, and for perseverative vs. anticipatory coarticulation

High frequency centroid Results: Adults, anticipatory intercept3737 Hz main effect round vowel-31 Hz No effect of measurement location. Adults begin anticipating an upcoming round vowel at fricative onset. Adult High Frequency Centroids, Anticipatory measurement location 20% 80% non-round round i u

High frequency centroid Results: Adults, perseverative intercept3703 Hz main effect round vowel-45 Hz interaction72 Hz location:round Adults correct for perseverative lip rounding by the end of the fricative. Adult High Frequency Centroids, Perseverative measurement location 20% 80% non-round round i u

Amplitude ratio Related to tongue posture high ratio = palatal articulation Find peak above F2 region… mean amplitude in 1000 Hz band around high frequency peak – mean amplitude in 1000 Hz F2 region find peak here

Amplitude ratio Results: Adults, anticipatory intercept15.1 main effects location-1.1 round vowel-1.0 More palatal articulation at beginning of fricative, and in non-round context. Adult Amplitude Ratios, Anticipatory measurement location 20% 80% non-round round i u

Amplitude ratio Results: Adults, perseverative intercept13.4 no significant main effects interaction2.4 location:round Adult /s/ more palatal by the end of /us/ sequence. Adult Adult Amplitude Ratios, Perseverative measurement location 20% 80% non-round round i u

Kurtosis Correlated with lip rounding high kurtosis = more peaked distribution = more lip rounding Calculated following Forrest et al. (1988)

Kurtosis Results: Adults, anticipatory intercept3.1 main effect round vowel0.01 Adults show early anticipatory lip rounding, lasting throughout the fricative. Adult Kurtosis, Anticipatory measurement location 20% 80% non-round round i u

Kurtosis Results: Adults, perseverative intercept3.1 main effect round vowel0.05 interaction-.07 location:round Lip rounding disappears by the end of the fricative. Adult Kurtosis, Perseverative measurement location 20% 80% non-round round i u

Summary: Adult results Adults begin anticipating upcoming round vowel at fricative onset. Perseverative coarticulation lasts into the beginning of the following fricative, but is greatly reduced by the end.

High frequency centroid Results: Children, anticipatory intercept5697 Hz main effect round vowel-20 Hz Children also begin anticipating round vowel at fricative onset, but to a lesser degree. Preview: lack of effect on kurtosis may indicate this difference is due to PoA, not lip rounding. Child High Frequency Centroids, Anticipatory measurement location 20% 80% non-round round i u

High frequency centroid Results: Children, perseverative intercept5693 Hz main effect location- 10 Hz round vowel- 20 Hz Perseverative effet lasts throughout fricative. Main effect of location < utterance final position of most fricatives? Child High Frequency Centroids, Perseverative measurement location 20% 80% non-round round i u

measurement location Amplitude ratio Results: Children, anticipatory intercept3.63 no significant predictors Child Amplitude Ratios, Anticipatory non-round round % 80% i u

Amplitude ratio Results: Children, perseverative intercept3.31 main effect location- 1 Main effect of measurement location < most fricatives being utterance final? Child Amplitude Ratios, Perseverative measurement location 20% 80% non-round round i u

Kurtosis Results: Children, anticipatory intercept1.81 no significant predictors Much lower values than adults (intercept = 3.1) Suggests lack of lip rounding: coarticulation observed in centroid data may have been related to PoA. Child Kurtosis, Anticipatory measurement location 20% 80% non-round round i u

Kurtosis Results: Children, perseverative intercept1.81 main effects location-.003 Again, no significant difference due to round vowel context. Child Kurtosis, Perseverative measurement location 20% 80% non-round round i u

Child vowel spectra

Summary: Child results Evidence for only gross motor control: – overall flatter spectrum < lack of tongue groove – lack of change/compensation in perseverative data – little evidence for lip rounding: differences in centroid may have come from PoA BUT children anticipate upcoming round vowels as early as fricative onset (even though the gestures used to produce both fricative and vowel are different from adults’) Suggests children’s planning is similar to adults’, but they lack the motor control needed to produce adult-like articulation

Comparison with previous findings Zharkova et al. (2011b) concluded children don’t have differential control of tongue tip vs. dorsum by 7;7 – Our data are consistent with this conclusion – Also consistent with Nittrouer’s (1995) conclusion that different types of gestures develop along different timescales Most previous studies have not looked at the interaction between age group and direction of coarticulatory influence.

Conclusion We identified several acoustic measures that reveal fricative-vowel coarticulation in spontaneous speech. Similarities between adults and children: – planning – constraints on articulation Difference: – Motor control necessary to compensate for constraints

Thank you! (especially to Barbara Davis and Brian MacWhinney for making the child data available, and to Vanessa Chew for help segmenting fricatives)

Future work Investigating additional variables: – random effect for word, for adults – age effects, for children – individual variation – lexical predictors (word frequency, neighborhood density) – control for neighboring segments, speech rate – compare within- vs. across-word coarticulation

Adult fricative spectra

Adult vowel spectra

Child fricative spectra

Child vowel spectra

Examples of child speech Cameron, age 22 months Rebecca, age 17 months

Child data