This study aimed to identify the phonetic differences between standard pronunciation and actual pronunciation of the special particle ‘-yo’ by examining speech variations shown in the The Korean Corpus of Spontaneous Speech(Seoul Corpus 2015). The standard phonetic form of ‘요’ [yo] appeared only about 12%, while the ‘여’[yə] variant appeared 84%, and other types―‘녀, 어, 뇨, 염, 오, 념, 려, 연, 영, 용, 유’[nyə, ə, nyo, nyəm, o, nyəm, ryəm, yən, yəŋ, yoŋ, yu]―appeared 4%. The study found that male group used the standard pronunciation of [yo] more than female group, and teenagers spoke in a standard form of ‘-yo’ more than the other generations. These findings are contrary to those of previous studies, in which women rather than men and the younger generation rather than the older use non-standardized forms of language. It would be noteworthy to examine the discrepancy between spontaneous speech in a laboratory environment of interview and in real-life situations. (Daegu Cyber University)