We compare the vowel systems of Finnish, Mongolian (in China) and Udmurt, and illustrate the average placements of their monophthongal vowel types on F1/F2 plots. Mongolian has more vowel phonemes (12 long and 12 short ones) than Finnish (eight long and eight short) and Udmurt (seven). Some basic linguistic characteristics and key word lists of the three languages are presented. For comparison we utilise psychoacoustical F1/F2 formant charts which are fairly good approximations to the vowel space. The phoneme distances are indicated by means of circles of 1 Bark diameter centered on the mean F1/F2 points of the vowel types. This kind of representation allows one to draw conclusions about qualitative vicinity, partial overlapping or even merging of phoneme qualities on F1/F2 plots and about the necessity of further acoustic parameters for vowel differentiation. We also discuss some centralisation phenomena in the three languages.