Manipuri language is one of the low resourced languages of north eastern part of the India. The need of development of speech technology in the local language is of urgent demand, so as to improve the livelihood of the people. The pre-requisite of development of such speech technology requires the basic research on the acoustic phonetic of the phoneme together with the development of speech resources. Keeping the main objective in mind the current paper aims at preliminary study on acoustic characteristics of Manipuri vowel. The current study is conducted on the speech corpus of around 500 Phonetically Balanced Words (PBW) embedded in neutral carrier sentences spoken by ten informants (5 male and 5 female) in a reading mode. The dialect chosen for the purpose of experiment is Imphal dialect of Manipuri language. After analyzing the data, vowel phoneme inventory of Manipuri language has been presented in this paper.