Objective: To investigate voice function following Han's uvulopalatopharyngoplasty. Patients and methods: Acoustic and articulatory function was examined by acoustic analysis and by formant frequency and bandwidth analysis, before and after Han's uvulopalatopharyngoplasty, in 56 patients with obstructive sleep apnoea hypopnoea syndrome. Results: These patients' normalised noise energy was higher than normal, and improved post-operatively. Their pre-operative F-1, F-2, and F-3 formant frequencies and B-1 and B-2 formant bandwidths were significantly lower than those of normal controls; however, one month after surgery their F-1 and F-2 frequencies were markedly higher. Conclusion: The acoustic and articulatory characteristics of obstructive sleep apnoea hypopnoea syndrome patients differed from those of normal subjects. After Han's uvulopalatopharyngoplasty, obstructive factors in the oropharynx were relieved, allowing oropharyngeal cavity expansion and a gradual increase in formant frequency to within the normal range. Patients' vocal quality improved and their resonator and articulator functions were protected and enhanced.