Degree Name

Master of Science (MS)

Semester of Degree Completion


Thesis Director

James E. Nicely


The purpose of this study was to examine, from a phonological and morphological point of view, two-year old children's utterances of final /s/ and final /z/ in singular (CVC) and plural (CVCC) forms.

The subjects were 32 two-year old children who attended day-care centers. There were 13 males and 19 females, ranging in age from 26 months to 36 months, with an average age of 29 months.

In a 16 item test, each of the 32 children named eight singular nouns (/bʌs/, /haus/, /fers/, /maus/, /nouz/, /tʃiz/, /rouz/, /hous/) and eight plural nouns (/kʌps/, /hæts/, /keɪks/, /sɑks/, /bɔlz/, /gʌnz/, /bɛdz/, /dɔgz/) ending in /s/ and /z/. The utterances of final /s/ and /z/ were studied for differences in production. The number of distinctive and descriptive features that had been used correctly were analyzed for each utterance with /s/ and /z/ in different morphological contexts (CVC, CVCC). The number of correct features were also compiled for each singular (CVC) and plural (CVCC) response.

Two-year old children in this study:

  1. Uttered final /s/ correctly in 54% of 256 responses and final /z/ correctly in 2% of the 256 responses. Since the only feature difference between /s/ and /z/ is the voicing element, the results imply that the added feature of voicing reduced the mean number of correct /z/ utterances as defined by the distinctive and descriptive features used in this study.
  2. Uttered correct final /s/ more frequently than correct final /z/ regardless of the morphological environment.
  3. Used alternate phonemes that closely approximated the distinctive and descriptive features for /s/ and /z/, when /s/ and /z/ appeared too difficult to produce. The most common substitution for /s/ was /θ/. The most frequently occurring distortion was dentalization, /s̪/. The descriptive feature [-lateral] was also employed to describe distortions, however no occurrences of lateralization were heard for /s/ or /z/ utterances.
  4. Produced singular word responses (CVC) correctly more often than plural word responses (CVCC).
  5. Displayed morphological patterns of pluralization in the absence of correct phonological systems.

The consistent superiority of correct /s/ utterances over correct /z/ utterances substantiated the phonological patterns reported in the literature for older children, however, the results contradict the frequent assumption that final /s/ and /z/ are not acquired until children are of school age.

The ability to produce plural inflections was also reported in the literature as being a skill acquired by preschool and grade school children. The results have shown that children as young as two-years old had the ability to express plurality. Therefore, the results of this study suggested that the phonological and morphological skills of children are in the process of development prior to the previously reported ages of five through seven years.