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requisite processes required for a skill. I.n Fiona’s case, the 
timely emergence of her speech was likely constrained by ’
having insuflicient control and coordination of the systems 7' ' ’
and structures required for speech, including the speech ‘,_
articulators (the tongue, lips, and jaw). This is not uncom- l ‘M.
mon among children who are otherwise typically develop- _ _
ing. Among two year olds, about one in five do not yet com- ‘ v V I '
bine words as would be expected by this age (Zubrick et al., 3' I l ' e g
2007). The development of speech motor control is the most < i ‘ ' 3 ~\
likely constraint for babies and toddlers as they work toward .-I \ — F
producing their first words (Moore, 2004). ‘ E
Speech motor control refers to the integration of inputs from . ‘ l V
the brain to control the activation of muscles and structures ‘ , -‘
to produce the skilled movements required for speech. The  ‘i
inputs must coordinate exhaled breath, Voice, the move- ‘w l‘ ‘.
ments of the articulators, and even the stiffness or laxness e '
of the cheeks; speech requires conscious neural control and Figure 2. Infant-directed speech is common to most of the
coordination that is unparalleled in the repertoire of skilled ‘_W’ld’5 ]“"X““g€5 “ml ”‘h“”“5 l“”g““.¥‘ l€“’”i”g- Ph"”’/”"m
movements. This is big work for a baby! This advanced con- “m£kph°t°'wm'
trol emerges gradually over the course of infancy and child- 
hood, with adult-like control and stability not achieved until stage emerges end Includes dearer Vowel sounds‘ eqheele’
adolescence (Smith and Zelaznik 2004)‘ yells, raspberries, and other Vocal play sounds. Tlus stage
can be really noisy (see Multimedia File 3 at acousticstoday.
Learning ‘his Comm] for 5P99Ch P‘°d“C‘-lo“ 055"“ 3”d“' org/mm-Vick), but it is an important precursor to the clearly
ally through the building on skills that are either innate to formed syllables mm; are aim,“ to ,,merge_
the newborn or develop in early infancy (MacNeilage and _ _ _ _
Davis, 2000)‘ Any Parem will tell you mm right from me Whatwe thinkof as babbling, the combination of consonants
start, a baby can express itself and that it does so loudly and and Vowels repeamd ‘NH and 0V9! (e.g., babababa ), tends
frequently. At birth, an infant is able to produce a cry, but eh emerge helweeh 6 and 10 m°ht_he_°f_age‘_"ght emhhd ‘he
soon gooing and babbling emerge, which are imponant Pre_ time that the baby becomes a specialist in discriminating the
cursors to early speech development (Oller, 1980). These be- sounds of the" 0_wh language Eve‘: those sf hfher lhn_ghagee'
haviors follow a predictable pattern, beginning with a stage Lher’ this hahhhhg becomes Zanegeted” whh Vheymg syl-
of nonresonant vowel-like sounds in the first two months. In hhhe shapes and sounds (e‘g" hedhhede)’ lhet Pm” to ‘he
this) the uphonauon, stage, Fiona was able ‘O Produce long emergence of the first words. These vocalizations herald the
vowenike sounds and she seemed ‘0 exchange ‘hem with emergence of true syllable structure, exciting for both the
me in a dialogue. In this sample (see M “Mme din File 1 at linguist and speech therapist moms to witness. Understand-, when Fiona was two months ably’ hlehy Pheehte hegm ehhlhhg these Pmdhehohe mm
old, it is clear that she is working to control her voice and _words by eeeoaeemg them whh objects or People the‘ are
seems to be moving her jaw a small a.mount, which has hhphreehe‘ repeehhg the eyhehles ehd Pomhhg hnel‘ “In-
only a subtle impact on shaping the Voice. Following this) mately, using-the syllables in responsive exchanges with the
the “gooing” stage emerges at two to three months when the baby‘ as seen  “he Vhleo from wheh Fiona was he mohthe
baby combines the vocalizations with guttural consonant- °1d_ (see Mhlhmeehe Fhe 4 3‘ e_e°“ehe:mdeY'oeg/mm'\:ek)'
like sounds, the most primitive articulation. The gooing In n’ she Pmdheee heeIme“1‘ee"hge”°f m_ememhme'ma’ hue
stage reflects the infant learning to use the tongue and lips I _reP 1? by asking her ‘O my Dede’ ehalhhg and explmhhg
to articulate the voice into something like speech sounds, Fumes Voehlplhh
although very primitive, as can be seen here when Fiona was For the baby, these strings are madein many contexts,
three months old (see Multimedia File 2 at acousticstoday. most of which are not communicative at all. It seems, instead,
org/mm-Vick). At four to six months of age, the “expansion” that the baby uses these productions to explore a.nd learn the
Fall2018 | Acoustic: Tnday | 41

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