The aim of the study was to characterize the acoustics of vowel articulation in maxillectomy patients. Digital acoustic analysis of five vowels, /a/, /e/, /i/, /o/ and /u/, was performed on 12 male maxillectomy patients and 12 normal male individuals. A simple set of acoustic descriptions called the first and second formant frequencies, F1 and F2, were employed and calculated based on linear predictive coding. The maxillectomy patients had a significantly lower F2 for all five vowels and a significantly higher F1 for only /i/ vowel. From the data plotted on an F1-F2 plane in each subject, we determined the F1 range and the F2 range, which are the differences between the minimum and the maximum frequencies among the five vowels. The maxillectomy patients had a significantly narrower F2 range than the normal controls. In contrast, there was no significant difference in the F1 range. These results suggest that the maxillectomy patients had difficulty in controlling F2 properly. In addition, the speech intelligibility (SI) test was performed to verify the results of this new frequency range method. A high correlation between the F2 range and the score of SI test was demonstrated, suggesting that the F2 range is effective in evaluating the speech ability of maxillectomy patients.

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The factors affecting HRQL in the maxillectomy patients were different from those in the mandibulectomy and/or glossectomy patients. Though they wore stable prostheses; we were still able to show that resection size, radiotherapy and neck dissection affected HRQL.

We found that the psychoacoustic parameters typically adopted in industrial research could also be applied to evaluate the psychoacoustics of the monosyllable /sa/ utterance, and distinguished the monosyllable /sa/ in maxillectomy patients with an obturator from that without an obturator using the system.

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Among the functional disabilities that patients face following maxillectomy, speech impairment is a major factor influencing quality of life. Proper rehabilitation of speech, which may include prosthodontic and surgical treatments and speech therapy, requires accurate evaluation of speech intelligibility (SI). A simple, less time-consuming yet accurate evaluation is desirable both for maxillectomy patients and the various clinicians providing maxillofacial treatment. This study sought to determine the utility of digital acoustic analysis of vowels for the prediction of SI in maxillectomy patients, based on a comprehensive understanding of speech production in the vocal tract of maxillectomy patients and its perception. Speech samples were collected from 33 male maxillectomy patients (mean age 57.4 years) in two conditions, without and with a maxillofacial prosthesis, and formant data for the vowels /a/,/e/,/i/,/o/, and /u/ were calculated based on linear predictive coding. The frequency range of formant 2 (F2) was determined by differences between the minimum and maximum frequency. An SI test was also conducted to reveal the relationship between SI score and F2 range. Statistical analyses were applied. F2 range and SI score were significantly different between the two conditions without and with a prosthesis (both P < .0001). F2 range was significantly correlated with SI score in both the conditions (Spearman's r = .843, P < .0001; r = .832, P < .0001, respectively). These findings indicate that calculating the F2 range from 5 vowels has clinical utility for the prediction of SI after maxillectomy.

Many papers have been published on surgical mandibulectomy and reconstruction. However, only a few reports refer to masticatory function after prosthodontic treatment in mandibulectomy patients. The aim of this study was to investigate the masticatory function of mandibulectomy patients. Twenty-three subjects (10 males and 13 females, with an average age of 63 years) participated in this study: 11 subjects who had undergone unilateral marginal mandibulectomy, six subjects with unilateral segmental mandibulectomy with reconstruction and six subjects with hemimandibulectomy without reconstruction. Mixing Ability Index (MAI) was used to measure masticatory function on the non-defect side and on the defect side with a prosthesis installed. Comparisons were carried out among the marginal, segmental and hemimandibular groups and between the non-defect side and the defect side. Consequently, our study indicates these results. On the non-defect side, a significant difference was found between the marginal and the segmental groups, and between the marginal and the hemimandibular groups. In the marginal and the segmental groups, a significant difference was found between the non-defect and the defect sides. In conclusion, our study suggests that MAI is an adequate tool to study the masticatory function in mandibulectomy patients, the masticatory function of the mandibulectomy patients is more impaired than that of the ordinary removable partial denture patients, and that surgical intervention affects the masticatory function on not only the defect side but also the non-defect side in mandibulectomy patients.

It was indicated that the automatic conversation intelligibility test system using sentences as stimuli would be effectively used in evaluating maxillectomy patients' speech.