A review regarding indicators used in Korean research is needed to develop a diagnostic marker system for Korean children with speech sound disorders (SSD). This literature review examined the research conducted to reveal the characteristics of children with SSD of unknown origin in Korea. The researchers in Korea used diverse variables as indicators to identify the natures of children with SSD. These included indicators related to external characteristics of speech sound and comorbid features other than external aspects of speech sound. The attention has been focused on specific indicators so far. This result implies that some indicators may still require closer study in various aspects due to their influence, and some may require more attention due to the limited number of research. This article argues that more research is necessary to comprehensively describe the unique characteristics of children with SSD of unknown origin and suggests a direction for future research regarding diagnostic markers and subtype classification of SSD. It also proposes potential diagnostic markers and a set of assessments for the subtype classification of SSD.

Objectives: This study aims to examine Korean and English research trends regarding language development and language impairment, and to suggest future directions for later research. Methods: Sixty-five Korean research papers published in Communication Science & Disorders and 129 English research published in the Journal of Speech, Language, and Hearing Research were classified according to the subject, time dimension, observational method, independent variable, and dependent variable. The frequency and rate of publication of each type were yielded. Results: Nearly half of the subjects were typically developing toddlers, but there were some differences between the research in the two journals. Cross-sectional studies had higher rates in Korean research, and longitudinal studies had higher rates in English research. In Korean journals, most articles were descriptive studies, with very few experimental studies. In English journals, various independent variables were used relatively evenly, whereas the variables related to the characteristics of the subject were used at higher rates in the Korean journals. Both journals mostly used variables associated with expressive language as dependent variables. Conclusion: Although more research has been published and the types of studies have become more diverse than in the past, during the recent decade in Korea the amount and types of studies are limited when compared to English research. In this regard, this study discussed the direction in which future research related to infant language disorder should proceed.

Objectives:This study provides readers with information about the stimulus words of 4 Korean standardized tests for speech sound production and compares test results of children with speech sound disorders through the 4 tests. Methods: In Experiment 1, 4 tests were conducted on 15 children who have speech sound disorders. The test results were compared in terms of percentage of consonants correct (PCC) and standard deviation score. In Experiment 2, the stimulus words of the 4 tests were compared in terms of complexity and the number of opportunities for production of consonants Children's phonetic inventories were also compared. Results: In Exoperiment 1, there were significant correlations among the PCC of whole words in the 4 tests and the PCC of target phonemes in the 4 tests. However, the range of standard deviation in which children were included, and phonetic inventories varied with each test. In Experiment 2, the 4 tests provided different numbers of opportunities for production of consonants across each word position. None of the tests provided more than two opportunities for the production of each consonant.The tests varied in terms of phonological mean length of utterance (PMLU) of words that elicited the production of each of the consonants, and this led to differences in children's phonetic inventories. Conclusion: The results of this study provide clinicians with information that can assist them in selecting the ideal test for their clients. This study showed that there are limitations that exist in the current standardized tests for completing phonetic inventories. Clinicians will need to understand these limitations and conduct additional supplemental tests to compensate for the shortcomings.