The goal of this paper is to explore the effects of changes in velar coupling area and oral cavity configuration on the poles and zeros introduced in the nasalized vowel and nasal consonant spectra due to the sphenoidal and maxillary sinuses. MRI data for the vocal tract and nasal tract of one speaker was used to simulate the spectra of the nasalized vowels /A, æ, i, u/, and nasal consonants /m, n/ with different coupling areas. It is shown that during nasalized vowels, the frequencies of both poles and zeros due to the sinuses change with a change in the velar coupling area or the vowel. It is also shown that during nasal consonants, the zero frequencies are constant, and the pole frequencies are more stable as compared to nasalized vowels. This study, therefore, corroborates the use of nasal consonant spectra for speaker recognition and raises doubts on the potential benefits of using nasalization during vowels for that purpose.