University of Groningen. On vibration properties of human vocal folds Svec, Jan

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1 University of Groningen On vibration properties of human vocal folds Svec, Jan IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2000 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Svec, J. (2000). On vibration properties of human vocal folds: voice registers, bifurcations, resonance characteristics, development and application of videokymography Groningen: s.n. Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date:

2 Chapter 10 Addendum CHAPTER 10 Addendum

Švec: On Vibration Properties of Human Vocal Folds 109 ADDENDUM Videokymography proved to be a very useful tool which allows to obtain detailed information on the dynamic behavior of the vocal folds

Figure A1 complements the results from Chapters 2 and 4 and reveals the change of vibratory pattern of the vocal folds at the moment of the chest-falsetto leap, as viewed in videokymography.

4 Švec: On Vibration Properties of Human Vocal Folds 109 ADDENDUM Videokymography proved to be a very useful tool which allows to obtain detailed information on the dynamic behavior of the vocal folds during chestfalsetto transitions. Below, there are presented some examples which were presented to international conferences [1 5] and are in preparation for future publications. Figure A1 complements the results from Chapters 2 and 4 and reveals the change of vibratory pattern of the vocal folds at the moment of the chest-falsetto leap, as viewed in videokymography. At the beginning of the transition, the vocal folds vibrate in chest (modal) register at the frequency of ca. 200 Hz. The closure of the vocal folds is untypically short for the chest vibratory pattern, however. The vibration successively looses its simple shape and the pattern is modified by a ripple which increases from cycle to cycle until the vibration instantly shifts into a falsetto pattern with the resulting frequency of ca. 300 Hz. Figure A1 shows that the vibration is not really disordered during the abrupt chest-falsetto transition, as it has been assumed from the investigations of Rubin and Hirt [7]. Both the vocal folds vibrate synchronously during the transition with a distinct (complex, rippled ) pattern. The shift from the rippled to falsetto pattern (causing the actual sudden change of frequency of voice) is accomplished within almost a negligible time interval of one vibration cycle (ca. 3 ms). Accomplishment of such a quick change of frequency lies far beyond the capabilities of laryngeal muscles in terms of their maximal contraction speed [6;8], and gives strong evidence that such a change of frequency is a bifurcation phenomenon. Figure A2 presents a sequence of videokymographic images showing the formation of the subharmonic vibratory pattern observed in Chapters 2 and 3. The simple-shaped glottal cycle (of the chest register) successively transforms into a subharmonic pattern Fig. A1. Chest-falsetto jump as viewed in the sequence of eight consecutive videokymographic images. The same subject as investigated in Chapters 2, 3 and 5. The frequency transforms from ca. 200 Hz to ca. 300 Hz. The measuring position was approximately in the middle of the vocal folds, perpendicular to the glottis. (Concatenation of the VKG fields was done by the same method as used in Chapter 9). Fig. A2. Eight successive videokymograghic fields showing the change from normal (chest register) to a subharmonic vibratory pattern of the vocal folds. The frequency transforms from ca. 150 Hz to ca. 75 Hz. The same subject as investigated in Chapters 2, 3 and 5 The measuring position was approximately in the middle of the vocal folds, perpendicular to the glottis.

pattern. The resulting superposed signal (top) shows features similar to the PGG and EGG signals in Fig. 2 in Chapter 3.

5 110 Chapter 10: Addendum Fig. A3. Simulation of a superposition of two sinusoidal vibrations with the fundamental frequencies related by the f 2 :f 1 = 3:2 ratio, which shows the possible mechanism of creation of a subharmonic pattern. The resulting superposed signal (top) shows features similar to the PGG and EGG signals in Fig. 2 in Chapter 3. which is composed of two glottal cycles, the first simpleshaped, the second one rippled. The rippled shape of the glottal cycle observed here indicates a relationship with the unstable vibratory pattern observed at the moment of chest-falsetto transition in Fig. A1. An interesting role seems to be played by the 3:2 ratio observed in this subject as the typical magnitude of the chest-falsetto leap (Chapter 2) as well as the ratio between the two lowest resonance frequencies of the vocal folds (Chapter 5). The 3:2 ratio is hypothesized to play also a role for the formation of the subharmonic pattern of the vocal folds (Chapter 3). The possible mechanism is illustrated in Fig. A3. The figure presents a simple simulation of combination of a stable sinus vibration (frequency 140 Hz) to which a second vibration with a frequency 210 Hz (e.g., 3/2 times higher than 140 Hz) and a successively increasing amplitude is added. For simplicity, the nonlinear effects are neglected here. The result is a complex vibration with a subharmonic pattern which in many aspects resembles the subharmonic pattern of the real vocal folds (compare Figure A3 to A2 and also to Figure 2 in Chapter 3). In accordance with the results of Chapter 5, the two vibrations illustrated in Figure A3 might be related, e.g., to the modes x-1 and x-2. While the contribution of the x-2 mode to the complex subharmonic vibratory pattern would not be surprising, the role of this mode in the mechanism of the chest-falsetto transition has not been expected, since in neither of these two registers the anterior- Fig. A4. A patient (male, age 22) suffering from a mutational voice disorder (prolonged mutation). (A) Breathing. (B) Closed and (C) open phases of the vocal folds vibrating in a chest register as seen in videostroboscopy. Images (D, E, F) show vibration of the vocal folds in falsetto register. The images from the open phase of this register (D, E) reveal anterior-posterior differences which indicate the presence of the mode x-2. An almost complete glottal closure, except of a small gap in the posterior part, is visible in (F). posterior differences, typical for the x-2 mode, have been reported. However, in our latest investigations of patients with mutational dysphonia, suffering from voice instability and occurrence of spontaneous chest-

Švec: On Vibration Properties of Human Vocal Folds 111 falsetto leaps in speech, the anterior-posterior differences were detected (Figs. A4 and A5).

6 Švec: On Vibration Properties of Human Vocal Folds 111 falsetto leaps in speech, the anterior-posterior differences were detected (Figs. A4 and A5). This finding indicates that the x-2 mode might, indeed, play some role in the production of spontaneous chestfalsetto leaps, at least in some subjects. The initial data from Chapters 2 and 5 are in accordance with the hypothesis expressed in Chapter 2 that the magnitude of the pitch jump during chestfalsetto transition is related to the adjustment of the (lowest) resonance frequencies of the vocal folds. If such a relationship would indeed exist, the information on magnitude of the frequency jump during abrupt chest-falsetto transition might be used to derive information on the resonance properties of the vocal folds which are highly problematic to measure. More investigations and data from more subjects are highly needed to confirm this hypothesis, however. Unfortunately, the experiments put rather high demands on the investigated subjects in terms of the ability of voice control, which makes gathering of the data from large amount of subjects not an easy task. Nevertheless, the initial results obtained within the dissertation appear promising in terms of providing fundamental data on the biomechanical properties of the vocal folds. The initial results obtained from applying videokymography to basic as well as clinical investigations of voice prove that videokymography can be helpful in obtaining new, detailed information on the vibration properties of the vocal folds as well as to contribute to a more objective diagnosis of voice disorders. Fig. A5. Videokymographic images of an abrupt chest-falsetto transition in the same patient as shown in Fig. A4. The measurement position is indicated in Fig. A4 (B and E). (G) Detail of the vibratory pattern of the chest register (frequency ca. 100 Hz) with a prominent long closed phase. (H) Detail of the falsetto register (frequency ca. 400 Hz) with a short closed phase and smaller amplitude of vibration. (I) Chest-falsetto jump (the frequency transforms from ca. 200 Hz to ca. 390 Hz). Note the transition pattern within the time interval between ms. (J) Falsetto-chest jump (the frequency transforms from ca. 370 Hz to ca. 190 Hz). A complex vibration pattern can be seen during the transition between ms.

7 112 Chapter 10: Addendum REFERENCE LIST [1] Švec JG, Schutte HK, Šram F: Voice Registers in the Light of Videokymography. (Lecture). 26th Annual Symposium: Care of the Professional Voice. Philadelphia, PA, June 2 7, [Presented by J. Švec]. [2] Švec JG, Schutte HK, Šram F: Videokymography: Introduction, Vibration of Normal Vocal Folds, Voice Registers. (Lecture). 2nd Round Table Advances in Quantitative Laryngoscopy using Motion-, Image- and Signal Analysis. Erlangen, Germany, July 18 19, [Presented by J. Švec]. [3] Berry D, Švec JG: A gentle whiff of chaos from patients, singers and experiments. (Lecture). 28 th Annual Symposium: Care of the Professional Voice. Philadelphia, PA, June 2 6, [Presented by D. Berry and J. Švec]. [4] Švec JG, Šram F, Schutte HK: Sudden Changes in the Vocal Fold Vibration: Videokymographic Observations. (Lecture). PEVOC III, 3 rd Pan European Voice Conference. Utrecht, the Netherlands, August 26 29, [Presented by J. Švec]. [5] Šram F, Švec J: Results of Videokymographic Examinations by Functional Voice Disorders/Die Resultate der Videokymographie bei funktionellen Stimmstörungen. (Lecture). Deutsche Gessellschaft für Phoniatrie und Pädaudiologie Wissenschaftliche Jahrestagung, Marburg, Germany, October 1 3, [Presented by F. Šram]. [6] Alipour F, Titze I. Active and passive characteristics of the canine cricothyroid muscles. J Voice 1999; 13(1): [7] Rubin HJ, Hirt CC. The falsetto. A high speed cinematographic study. Laryngoscope 1960; 70: [8] Sundberg J. Maximum speed of pitch changes in singers and untrained subjects. J Phonetics 1979; 7:

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