wLocke (1983) Three mechanisms for phonological development:

1. Maintenance of those sounds from the babbling repertoire that fit the adult system.

2. Learning of new sounds to increase the repertoire.

3. Loss of sounds from the babbling repertoire that are not phonemic in the language.

Phonology of first 50 words

1. Syllable shapes -- CV, CVCV

2. Manners -- stops, nasals, glides

3. Place -- alveolar, bilabial

4. Phonetic inventory -- approx. 12

Acquistion of sound classes

Nasals

a) Nasal sounds occur early

/m/ and /n/ are among the first sounds to develop

/ng/ develops later

Other sound classes are rarely substituted for nasals, but when substitutions do occur, they are likely to be stops.

Stops

b) Also early developing sounds

/p/ and /b/ develop first

No clear-cut evidence for an order between /t/ and /d/, /k/ and /g/.

Substitutions often occur within the sound class; usually voicing or place

Hare (1983) found substitutions of k/g and g/k followed by t/k and d/g to be most common at 2yrs.

wBy 4yrs., Bassi (1983) found no errors on /g/ and only scattered errors on /t,d,k/.

Initially, children do not produce a distinction between the voiced and unvoiced cognates.

Macken and Barton (1980) indicate that the earliest production may be a voiceless unaspirated stop, which combines features of both cognates.

wTheir VOT (voice onset time) may not match the adult model and adult may not perceive the difference.

Dyson (1986) examined acquisition of velars by 2 year olds. She found that over the period of 2;5 to 2;10, the % of children producing 95% to 100% correct velars increased form 50% to 70%. Final velars were acquired before initial velars.

When in error, final velars were likely to be deleted than fronted as were initial velars. Seemed to be related to FCD (final consonant deletion).

Fricatives & Affricates

c) Labiodental /f/ develops much earlier than other fricatives, but its voiced counterpart /v/ remains later.

Doesn't appear to be a strong order for other fricatives, although both "th" 's are usually acquired later.

wFricatives may be easier to produce in the postvocalic position (Edwards, 1979; Edwards & Shriber, 1983), but Kenney and Prather (1986) did not find this to be true for /s,f,sh,or voiceless th/

Incorrect production of fricatives may reflect very different error patterns. Stops and affricates may be substituted for fricatives before a child has developed the continuancy or fricative features. Liquids or glides may be substituted.

wErrors by older children are more commonly place errors shown by replacement of a fricative by another fricative.

Glides & Liquids

d) /w/ and /j/ are acquired early whereas the liquids /r/ and /l/ appear late.

Usually a glide is substituted for a liquid before the liquid is acquired.

Remember that syllable-final liquids are very different from syllable-initial

forms. In the final position, liquids are usually omitted or replaced by vowels.

e) Most studies have found high error rates on /l/ and /r/ during preschool years. Most frequent substitution is /w/.

Clusters

f) Consonant clusters are usually acquired late. Olmsted (1971) found correct initial clusters to be extremely rare. Most are often reduced to a single consonant, which is usually the

unmarked (easier to produce) member of the pair.

g) In clusters with /s/, /s/ is frequently omitted. Exception: /sl/.

Phonological processes- systematic sound changes that affect a class of sounds or a sound sequence (Edwards & Shriberg, 1983).

Phonological process- regularly occurring deviation from standard adult speech patterns; may occur across a class of sounds, a syllable shape, or syllable sequence (Hodson & Paden, 1983).

wSummary - processes are descriptions of regularly occurring patterns observed in child speech which operate to simplify adult targets.

Deficient Patterns

•reduction to monosyllables: replacing multisyllabic words with a single syllable

• weak syllable deletion: omitting an unstressed syllable

wConsonant Clusters

•cluster reduction: omitting one or more segments of a cluster

• deletion: omission of the entire cluster

wConsonant Singletons

•postvocalic singleton omission: deleting a single consonant following the vowel in a syllable

• prevocalic singleton omission: deleting a single consonant preceding a vowel in a syllable

Glottal Replacements

•hat/ ha?

wIntervocalic

•bottle/ ba?o

Major Phonemic Substitutes

wWe believe that postvocalic liquid-plus-consonant sequences, as in /belt/ or /card/ should not be classed with consonant clusters as defined in omissions because the liquid is usually replaced by a vowel.

Stopping substituting stops for "non-stop" phonemes. Fricatives are the most common class replaced followed by sonorants.

wAffrication: substituting an affricate for a non-affricate /shoe-choe/

Deaffrication: replaces the target affricate with a continuant or stop phoneme /chair-shair/; /jump-dump/

Major Place Substitutions: substituting a phoneme in a nonadjacent place of constriction.

Fronting of velars: t/k and d/g; labial sounds may be used: p/k

wBacking: anterior phonemes replaced by back phonemes; e.g. k/t and g/d

Minor Place Shifts: substituting a phoneme in an adjacent place of constriction.

Palatalization: alveolar sounds shift backward to become palatals /soap-shoap/

Depalatalization: a forward shift of a palatal sound /shoe-sue/

Assimilations

altering a phoneme so that it takes on a characteristic of another sound in the word or phrase due to the influence of that other sound.

(ex. A child can produce /t/ in the initial position of a word /top/ but says /kwuck/ for /truck/ because the velar feature was assimilated from the postvocalic /k/)

Velar (as described)

Labial (pim/pin)

Nasal (num/thumb)

Alveolar (soot/foot)

Miscellaneous Deficient Patterns:

Coalescence: Replacement of two adjacent phonemes by a single new one which retains features from both of the original phones

(ex. foon/spoon the /f/ combines the stridency of /s/ and the labial place of /p/)

Metathesis: Reversal of the position of two sounds, as in ask /aks/ or animals /aminals/

Migration: Moving a phone to another position in the utterance quarter /kawer/

Reduplication: Repeating a syllable or a sound in a word in place of all the others, as in basket / baba/ or television /dedadida/

wEpenthesis - inserting a sound between two others.

Vowel Additions: adding a vowel in a word.

The schwa is sometimes inserted to separate the segments of a cluster (balack/black)

Voicing Alterations

wPrevocalic Devoicing: Replacing a voiced prevocalic consonant with a voiceless phone, as in pie/bye

Postvocalic Voicing: Replacing a voiceless postvocalic consonant with a voiced sound, as in leave/leaf

Vowel deviations

wQuite possible for vowel deviations to occur without affecting intelligibility

Need to be cautious about labeling variations which may reflect child's social or ethnic background

Most common deviations are substitutions of front vowels for front vowels; back for back (quadilateral)

Non-phonemic alterations

wDentalization - forward positioning for tongue-tip and/or blade consonants.

Lateralization - sound emission to the side(s) rather than centrally.

Nasalization - nasal emission during the production of typically non-nasal sounds.

Class deficiencies

wStridency deletion - this occurs when the strident feature is omitted/replaced.

Omission - /soap/ becomes /op/

Replaced - /soap/ becomes /top/

Velar obstruents - /k,g/

Liquid /l/ and /r/

Nasals - /m,n,ng/

Glides - /j,w/