1996 Fiscal Year Final Research Report Summary
The continuity of laryngeal adjustments in Fo control
| Project/Area Number |
07671852
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Otorhinolaryngology
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| Research Institution | Shiga University of Medical Science |
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Principal Investigator |
KITAJIMA Kazutomo Shiga University of Medical Science, Faculty of Med., Professor, 医学部, 教授 (10108996)
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| Co-Investigator(Kenkyū-buntansha) |
KATAOKA Hideyuki Shiga University of Medical Science, Faculty of Med., research associate, 医学部, 助手 (00224436)
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| Project Period (FY) |
1995 – 1996
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| Keywords | pitch / subglottal pressure / laryngeal muscles / laryngeal adjustment / voice register |
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| Research Abstract |
Purpose : The continuity of laryngeal adjustments in Fo control was investigated.
Methods : The supraglottal cavity was abruptly interrupted during sustained phonation, resulting in decrease of pitch. The amount of this pitch decrease was investigated, that is, the decrease of fundamental frequency (Fo) per unit change of supraglottal pressure (dF/dP) was calculated in human subjects. The values of dF/dP decrease with the elongation of the vocal folds and increase with increased stiffness of the vocal folds, indicating the behavior of this value against Fo reflects the two fundamental actions in the laryngeal adjustments for Fo regulation.
Results : 1. The values of dF/dP showed V-shaped change against Fo on the orthogonal coordinate system, dF/dP as the y-coodinate and Fo as the x-coordinate. The minimum values of dF/dP were observed around 200Hz in males and 250Hz in females. 2. The activities of thyroarytenoid muscle (TA) were in parallel with those of cricothyroid muscles (CT) in two subjects out of five ones. TA activity showed a plateau against CT activity in three subjects out of the five. These plateaus were noticed around 200Hz in males. 3. Latyngostroboscopy showed no correlation with the V-shaped change. 4. Air flow and subglottal pressure also showed no consistent relation with the V-shape. 5. The subjects with dry vocal folds induced by atropine injection showed smaller range of the values of dF/dP compared with that of the pre-atropine injection.
Conclusion : Incontinuity in Fo regulation was confirmed with the values of dF/dP.The stretching of the vocal folds plays the main role for Fo-raise till certain Fo (200Hz in males, 250Hz in females), then stiffness increase of the vocal folds takes over the main role exceeding these Fo's.
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