TIt is generally known that in Korean there is a three-way distinction in both manner and place of articulation classified as glottalized, lenis and aspirated consonants, and the same manner of classification applies to affricates, while fricatives are classified as two types, the glottalized and aspirated. Both the glottalized and aspirated types are always voiceless in any environment. The lenis type is voiced in word-medial position when both the preceding and the following sounds are voiced, but is voiceless in other environments. There are many acoustic, fiberscopic and electromyographic studies for differentiating the three manner categories of Korean consonants, but all of them are for Seoul and Taegu dialect. So authors tried to investigate acoustic features for Chonbuk dialect using acoustic waveform, fiberscopic features for the glottal width and electromyographic study for the role of the vocalis muscle in the word-initial and word-medial positions. The results were as follows : 1) By acoustic study with time waveform, voice onset time in word-initial position(/CVCV/) was longest in aspirated type followed by lenis and glottalized in word-initial position, but we could not check the voice onset time for the lenis in word medial position due to voiced phenomenon, the vocal cord vibration times for vowels(/CVCV/) in each consonants were not significantly different, and the oral closure time for word-medial stops(/CVCV/) is not significantly different between the aspirated and glottalized, whice the voice onset time for word-medial stops in longer aspirated than glottalized. 2) By fiberscopic studies, the glottal width in word-initial position in largest in aspirated followed by lenis and glottalized, and the glottal width in word-medial stops in largest in aspirated, but smallest in glottalized, whice there is no glottal width in lenis. 3) By electromyographic study using the vocalis muscle, the marked and earliest activation of the VOC muscles before voice onset of the following vowel, and lenis consonants by moderately activated, but glottalized consonants by marked activation of the VOC for the production of consonants in word-initial stops, but in word-medial stops.