Many of the studies dealing with speech perception of children have deleted redundancy of acoustic cues that were not inevitably needed to recognize the speech and compared the speech perceiving capability of children and adults. As a result, more of redundancy of acoustic cues was required by children than by adults to perceive speech. Several studies conducted on children and adults have used gating paradigm as a method for adjusting redundancy of acoustic cues. This method was suggested by Grosjean (1980) confirming the least of acoustic cues to perceive words. Edwards(2002) has utilized the gating in the study comparing the perception ability of final stop consonants of adults and also children aged 3 to 8 under typical development. As a result, a conclusion was made that children were in need of more of redundancy of acoustic cues than adults to perceive final stop onsonants. However, since final stop consonants in Korean language tend to be non unreleased, there was a limitation to confirm
the perception ability of final stop consonants of children in Korea only with the result of study by Edwards (2002).
Therefore, this study has used the gating on total 64 people including 16 children aged 4, 16 children aged 5, 17 children aged 6, and 15 adults identifying the development pattern of perception ability of final stop consonants. As for stimulus words, ''mokㄱ-motㄱ'' and ''papㄱ-patㄱ'' were used,
and preliminary experiment was conducted on adults confirming the additional redundancy of acoustic cues that were not inevitably required to perceive stimulus words. As a result of preliminary experiment, three conditions; when
providing all of acoustic cues of stimulus words of ''mokㄱ-motㄱ'' and ''papㄱ -patㄱ'', when deleting -40ms of redundancy of acoustic cues from final consonants, and when deleting -60ms of redundancy of acoustic cues from
final consonants, were manufactured. As for experiment tools, super lab version 4.5(model RB-834), response pad from super lab, laptop (LG X-note LGE-DMLGA51(B)), and headphone were used, and total 48 stimulus words in a condition with 4 stimulus x 3 conditions(gated condition: All, -40ms,-60ms) x 4 times were provided. As for measurement for confirming the perception ability of final stop consonants of test subjects, d-prime value was
used for reflecting the sensitivity of test subjects. As for statistical program, PASW 18.0 as well as two-way ANOVA repeated measure for confirming the perception ability of final stop consonants among four groups was used.
For the verification of difference inn dependent variables (condition: All, -40ms, -60ms) in each of the age groups, one way ANOVA was conducted. paired t-test was implemented to confirm the interaction effect. Results of this study are as follows. First of all, if providing all of acoustic cues of final stop consonants in stimulus words ''papㄱ-patㄱ'' children aged 4 were turned out to have significantly less of perception ability of final stop consonants than adults. If deleting -60ms of additional redundancy of acoustic cues from final consonants, children group of age 4 and 5 represented more difficulty in perceiving final stop consonants than adults. Children group of age 6
represented similar capability of performance with adults on aforementioned two conditions. Therefore, if providing all the redundancy of acoustic cues in stimulus words ''papㄱ-patㄱ'' it was shown that children started building
similar level of perception ability of final stop consonants with adults around the age of 5. If deleting additional redundancy of acoustic cues, they showed
a pattern of building perception ability of final stop consonants as similar as adults around the age of 6.
Secondly, if all of acoustic cues of final stop consonants in the stimulus words of ''mokㄱ-motㄱ'' were provided, an ability of perceiving final stop consonants was turned out to be significantly lower in groups of age 4 and 5 than in groups of age 6 and adult groups. After deleting -40ms of
additional redundancy of acoustic cues from final consonants, groups of age 4 and 5 were show to have more difficulty in perceiving the final stop consonants. Therefore, both cases of providing all of acoustic cues of final stop consonants and deleted redundancy of acoustic cues, an ability of perceiving final stop consonants was turned out to be similar with adult groups when children became around 6 years old. The reason why the development pattern of perception ability of final
stop consonants in the stimulus words of ''mokㄱ-motㄱ'' and ''papㄱ-patㄱ'', was that formant frequencies from Vowel-Consonant(VC) transition of the stimulus word ''mokㄱ'' was turned out to have less amount of changes.
Sussman (2001) has insisted that more clear and distinct redundancy of acoustic cues were needed by children than by adults for speech perception since children were less capable of utilizing the redundancy of acoustic cues.
Mayo & Turk (2005) have suggested stimulus words with much of changes in formant frequencies and also stimulus words with similar changes in formant frequencies identifying the speech perception ability of children and
adults. As a result, children represented a similar speech perception ability with adults in case of much of changes in formant frequencies. However, if the amount of change was similar, children represented a lower speech perception capability than adults. According to the changes in formant
frequencies based on VC transition of the stimulus ord ''mokㄱ'' in this study, changes were turned out to be less than other stimulus words. Therefore, since there was less of acoustic cue provided by ''mokㄱ'', children aged 4 and 5 seemed to represent more difficulty in perceiving final stop
consonants of the stimulus word ''mokㄱ''in the entire conditions.