The length of the vocal tract is correlated with body size which can be determined by using formant frequencies in speech. The interconnections between vocal tract length and formant frequencies are explored here. Recorded and computer-synthesized vowel sounds are used to gauge the vocal tract length of a speaker under consideration. Vocal tract length assessment may play an important role in ‘vocal tract normalization’, which is crucial for speech perception and language acquisition. Vocal tract length is analyzed by applying two methods namely linear predictive coding (LPC) and vocal tract constriction (VTC). Speech signal is produced by the convolution of excitation source and time varying vocal tract system components. These excitation and vocal tract components are to be separated from the available speech signal to study these components independently. To reduce the complexity of deconvolving the given speech into excitation and vocal tract system components the ‘Linear Prediction analysis’ is developed. The VTC evidence gives a measure of the very low frequency component present in the signal and hence gives different range of frequency values for different types of sounds. Zero frequency filtering (ZFF) is used to give an approximate measure of vocal tract constriction in terms of the low frequency component present in the speech signal.