This study aims to explore the phonetic symbols of two marked vowels in Lukang variety. In relatedliterature, the phonetic transcriptions for the two vowels vary; namely, they are considered as either thecentral vowels or the back vowels. This present paper uses the acoustic analysis, the observation of soundshift & phonology acquisition, and the inference of liaison phenomenon for further investigation. The resultsindicate that that the two marked sounds are close to central vowels [□] and [□] rather than the back vowels [□]and [□]. The marked central vowels are the strong bonds between group members, therefore, they should beproperly preserved.