‘k' is a sound that is present in many languages. However, for the Japanese language, ‘k' can be mistaken for ‘g' if the voice box in your throat is vibrating when you feel it . You can tell when it is voicing by placing your fingers in the area of the larynx as you pronounce the sound. If you do not feel any vibration, then it is ‘k'. In other words, vocal chord vibration or its absence makes a difference in the correct interpretation of the sounds produced which determine meaning (For details, please refer to the theory section.)
However, in some languages with regard to whether the speaker releases an extra puff of air or not when pronouncing ‘k' affects the meaning. For learners whose mother tongues have such characteristics, they tend to pronounce ga, gi, gu, ge, go ( が、ぎ、ぐ、げ、ご ) as k-sounds without releasing a puff of air and sounding like the Japanese ‘k' sound. When learners do this, Japanese will perceive those sounds as ka, ki, ku, ke, ko ( か、き、く、け、こ ) instead of ga, gi, gu, ge, go ( が、ぎ、ぐ、げ、ご ) . ( ガッコウ gakkou (school) → カッコウ kakkou ).
Moreover, there are some languages in which the presence or absence of vibration is determined by the position of a sound in a word, such as, ‘k' at the beginning of a word and ‘g' in the middle of a word. For speakers of such languages, although they are able to pronounce ga, gi, gu, ge, go ( が、ぎ、ぐ、げ、ご ) , when these sounds appear in the middle of a word; however, there are mistaken tendencies to pronounce them as ka, ki, ku, ke, ko ( か、き、く、け、こ ) when they appear at the beginning of a word. ( ガイコク gaikoku (a foreign country) → カイコク kaikoku ).Furthermore, there are incorrect tendencies to pronounce ka, ki, ku, ke, ko か、き、く、け、こ ) in the middle of a word as ga, gi, gu, ge, go が、ぎ、ぐ、げ、ご ) . ( カンコク kankoku (Korea) →カンゴク kangoku ).