Island is pronounced GAW with the short vowel AW and with a low tone. To make the vowel short, abruptly cut off your air flow. That is called a glottal stop. A mid-class consonant ก (G) that is ended with a short vowel is called a dead syllable and is automatically a low tone. The tone rules are complicated and you need to make a chart to refer to when trying to determine the tone of a syllable written in Thai characters . Every syllable in Thai has one of five tones. Island is transliterated on maps and in books as KOH but the vowel is not "O" and the initial consonant is not "K" but "G".