Hypernasality is a condition where the speech is highly nasalized resulting in significant reduction of intelligibility. Hypernasality happens due to severe leakage of air through nasal cavity because of either cleft palate and/or incomplete closure of velum. Hypernasality can be visualized as a phenomenon of introducing a nasal formant in the vicinity of first formant. To distinguish the nasal formant from the first formant, better spectral resolution is desirable. Traditional methods of formant extraction give average formant characteristics with 20-30 ms window size and poor resolution, when one pitch period is used. To overcome this poor resolution issue, especially for children speech case, this work proposes the use of zero time windowing (ZTW) technique. In ZTW, the speech signal is multiplied with a highly decaying impulse-like window of size approximately a pitch period. The loss in spectral resolution due to zero time windowing is restored by successive differentiation in frequency domain. Further the numerator of group delay is used to resolve closely spaced formants. The method when applied to hypernasal vowel sounds/a/,/i/and/u/gives accurate and better resolved location of nasal formant in the vicinity of first formant as compared to traditional methods. © 2016 IEEE.