The Vocal Tract and Speech Intelligibility of Tracheoesophageal Shunt Patients after Total Laryngectomy / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: In this paper, rehabilitation of voice after total laryngectomy has been suggested through the correct estimation and simulation of patients' vocal tract. Material and Methods: The author studied the shape of vocal tract during the phonation of five Korean vowels /u, o, a, e, i/ in tracheoesophageal shunt patients by magnetic resonance images (MRI). The same vocal tract was determined in each vowels from MRI. First, speech data produced by them were analyzed and also checked for speech intelligibility. Then the author tried to synthesize vowels from the vocal tract area of each vowels and from the expanded pharyngeal section of the vocal tract. RESULTS: The obtained results were as follows: 1) The sounds of /a/, /e/, /i/ were similar to natural sounds in actual patients' speech. The sound of /o/ was heard as /sigma/. The sound of /u/ was heard as strained /u/. 2) The synthesized vowels of /a/, /e/ from MRI were heard as natural sounds. The sounds of /u/, /o/, /i/ were heard as other sounds. 3) The synthesized vowel by the expanded pharyngeal section of 3 times in vowel /o/ was more naturally heard than that of 2 times. The synthesized vowel from Formfrek was more naturally heard than that from AreatoFormant. CONCLUSION: In conclusion, some of the synthesized sounds from MRI disagrees with the actual sounds produced by the subjects. This could be best identified by the synthesis from the area data. Future MRI studies should consider this problem for more accurate measurements. Also, pharyngeal areas with varied sizes should be experimented to secure better speech output because the correct shapes of vocal tract ensures correct vowel pronunciation.

An Acoustic and Radiologic Study on Voice Change after Tonsillectomy and Adenotonsillectomy / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Some patients who have undergone tonsillectomy complain of voice change, but few studies for the mechanism of voice change were found. To solve this problem, study of voice change after tonsillectomy and adenotonsillectomy was done. MATERIALS AND METHODS: We analyzed voice change of 22 patients who underwent tonsillectomy and 15 patients who underwent adenotonsillectomy at CSL (computerized speech laboratory), St. Benedict Hospital. With the measured cross sectional area of vocal tract and its length from the glottis on MR images, we presented the change of cross sectional area schematically after tonsillectomy. RESULTS: Acoustically, the frequencies of the second formant of /e/ and /i/ increased and that of the first formant of /u/ decreased significantly after tonsillectomy and the frequency of the second formant of /o/ and those of the second and third formants of /i/ and /u/ increased significantly after adenotonsillectomy. It was also showed acoustically that the formant bandwidths of /a/ and /hana/ after tonsillectomy and those of /e/ and /hana/ after adenotonsillectomy increased due to nasalization. Anatomically, it was showed that the cross sectional area of oropharyngeal cavity increased and coupling effect of vocal tract happened after tonsillectomy. CONCLUSION: This study showed that acoustic characteristics and vocal tract shapes of the patients did change following tonsillectomy and adenotonsillectomy. It is imperative that we explain to patients about the postoperative voice change. Research should also be done to find ways to induce better voice changes following the operations.

Mechanism of Vocal Phonation in T-E Shunt Patients after Total Laryngectomy / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Total laryngectomy has become a usual treatment for any advanced carcinoma of the larynx, but most patients who have undergone total laryngectomy have shown permanent disability in voice production. To solve this problem, studies of voice rehabilitation after total laryngectomy have been done. MATERIALS AND METHODS: We have developed an accurate method to measure the vocal tract shape along its length from magnetic resonance images acquired during the sustained phonation of Korean vowels by T-E shunt patients and normal subject. We estimated the accuracy of MRI and also compared the vocal tract spape of the normal and T-E shunt patients by comparing the first three formant frequencies estimated from MRI to those measured directly from speech data of the T-E patients and the normal subject. RESULTS: The length of T-E shunt patient's vocal tract is 17-18.5 cm. T-E shunt patients phonated strained voice. The length of resonant chamber of T-E shunt patients are shorter than that of the normal subject. The vocal tract is shortened during the phonation by T-E shunt patients. In cases of /e/ and /i/, front cavities are constricted while back cavities are shortened. The pseudoglottis of the T-E shunt patients is located at the region 14-15 cm from lip. CONCLUSION: Acoustic characteristics and vocal tract shapes of the T-E shunt patients are relatively similar to those of the normal subject. To achieve normal voice, reconstruction of pharyngeal and superior glottal resonant chamber will be desirable.