Speech, velopharyngeal function, and hearing before and after orthognathic surgery.

Articulation, voice, resonance, hearing sensitivity, and middle ear function were examined in 34 patients before and 3, 6, 9, and 12 months after orthognathic surgery. Thirty of the 34 patients had articulation errors before surgery. Errors on the sibilants /s/ and /z/ occurred most frequently, followed by those on /j,zh,ch/ and /sh/. Errors were predominantly distortions with both visual and acoustic components. After surgery, articulation improved spontaneously in the absence of intervention. Most of the preoperative articulation errors were eliminated by 3 months postoperative, but, thereafter, a gradual decline was noted so that by 12 months, errors occurred on /s/ and /z/. Voice, resonance, velopharyngeal port area, and hearing sensitivity were not altered by surgery. This study suggests that severe skeletal malocclusions requiring surgical correction have deleterious effects on the patients' articulation of consonants and that surgical alteration leads to the correction of most of these errors.