The evolution from final obstruents to final glottal stop and then to rhyme glottalization (i.e. from /at/ to /a?/, then to /a'/) is a well-established general trend in the history of the Sino-Tibetan language family and beyond. It has further been shown by laryngoscopy that in three languages which retain the nonreleased syllable-final obstruents /p/, /t/ and /k/ (Standard Thai, and two Chinese dialects), these obstruents are often accompanied by a glottal stop. The present research raises the issue whether there is another typological possibility: can nonreleased final obstruents be accompanied consistently by modal phonation, without glottal stop? Analysis of electroglottographic recordings of 126 syllables in two carrier sentences spoken by 4 speakers shows that, in Hanoi Vietnamese, the final obstruents /p/, /t/ and /k/ are not accompanied by glottalization, and that the open quotient increases in the course of the syllable rhyme. Obstruent-final rhymes (which may carry either of two tones: D1 or D2) are compared with nasal-final rhymes which, under one of the tones (tone B2), are confirmed to be glottalized. Our finding is that tones D1 and D2 (i.e. obstruent-final rhymes) are both produced in modal voice, which shows that the typological paradigm of observed realizations of syllable-final obstruents must be enlarged. The discussion puts forward the hypothesis that the unusual association of segments and voice quality found in Hanoi Vietnamese is a strategy to maintain the opposition between B2-tone and D2-tone rhymes.