Stroboscopy

Journal of Voice Vol. 6, No. 2, pp. 13%148 © 1992 Raven Press, Ltd., New York

Special Article

Stroboscopy Marie-Agnes Faure and *Andre Muller Department of Ear, Nose and Throat, Hospital of Besancon, France and *Private Practice, Lausanne, Switzerland

Summary: The history and principles of stroboscopy are reviewed, and stroboscopic findings during videolaryngoscopy are evaluated in relationship to the rest of the laryngological clinical evaluation to arrive at the bases for a stroboscopic semiology. Key Words: Diagnosis--Videostrobolaryngoscopy-Stroboscopy---Tumor.

Stroboscopy is as useful to the clinician as indirect laryngoscopy or laryngeal endoscopy because it allows evaluation of the dynamic aspects of vocal fold vibrations. Stroboscopic examination of the vocal folds provides information for a quick and precise phoniatric diagnosis that is useful for medical, functional, or surgical treatment, as well as for follow-up. Stroboscopy is of use to the phoniatrist, the ear, nose, and throat surgeon, the speech pathologist and, when used in conjunction with a video tape recorder, to the patient. Quite often phoniatric consultation is sought by professional voice users who have noticed slight breathiness, hoarseness, intensity difficulties, or changes of timbre within their phonatory range. Granted that many quality changes may have their origin in the vocal tract resonatory system or alterations in the laryngopharyngeal mucosa, clinical experience teaches that most difficulties are attributable to anomalies of the mucosal wave of the vocal folds. Stroboscopic examination permits assessment of the flexibility of the vocal fold (perfect, moderate, uni- or bilateral, total or partial). Stroboscopy may demonstrate suspicious phenomena suggestive of organic pathology that could be an obstacle to a professional career. We believe that stroboscopy is of great value to both the clinician and the professional voice user.

HISTORICAL BACKGROUND In Greek, strobos means whirling and scopein signifies watching or observing. Perello has described stroboscopy as "un m e t o d o creado para observar un organo que se m u e v e con un rnovimiento regular." The principle of stroboscopy

was simultaneously discovered by Plateau in Brussels and yon Stampfer in Vienna in 1833. It was first applied to laryngeal examination by Toepler in 1866; by 1878, Oertel had extended its use to laryngology. The eye cannot discriminate separate images that last <1/5 second because of the interaction between the length of the stimulus image and the persistence of the image on the retina. This explains why, to the unaided eye, the vibrating vocal folds seem to be stationary except for some low-frequency movements under certain conditions. The problem of resolving the too-rapid motion is solved by illuminating the larynx with brief flashes of light at a frequency just slightly less than their vibratory rate. Perello provides the example of a patient phonating at musical ut2, which is 128 Hz. Light flashes with a frequency of 127 Hz will slow the apparent vibratory rate to one glottal cycle per second, which provides a good slow-motion view of the glottic wave. According to Kitzing, the difference between the phonatory frequency and the rate of light flashes should be -1.5 Hz. The first mechanical stroboscope, called strobo-

Address correspondence and reprint requests to Marie-Agnes Faure, 32 Rue Coquilli6re, 75001 Paris, France.

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rama, was constructed by Sequin-Tarneaud; the first electronic stroboscope was built by Cary and Guillet in Paris in 1931. Commercialization of the instrument was accomplished by Timcke in 1956 (1). The first major publication on stroboscopy, Schoenharl's Die Stroboskopie in der praktischen laryngologie, appeared in 1960 (2). There have been many articles on the subject in medical journals, but the second overall review of the area has been prepared by Hirano and Bless (3). Present-day stroboscopes usually indicate the frequency of the phonatory signal and, occasionally, its intensity. With phase variability the dynamic aspect of the vocal folds can be assessed. It is common to couple the instrument to video recording systems to store results for research, teaching, and treatment. Speech pathologists, phoniatrists, and surgeons may also generate hard-copy prints of the video images to augment clinical records. Stroboscopy through a fibroscope is also possible. It allows the analysis of vowels less closed than /i/and/e/, but the image obtained is frequently too small and too blurred for careful analysis of mucosal wave patterns. Some researchers (4-7) have used a microscope to magnify the stroboscopic image. Wendler proposed telemicrostroboscopy in 1973 (8). In 1977 Kittel reported using color televideostroboscopy (9). Computerized manipulation of the stroboscopic image also holds considerable promise.

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GLOTTIC WAVE AND STROBOSCOPY Figure 1, modified from Hirano (10), illustrates the stroboscopic representation of the vertical motion of the mucosal wave, first suspected by Schonhad (11) and Smith (12). The glottic wave tells us about the status of the tissue situated between the superficial mucosa of the vocal fold (the cover), and the vocal muscle (the body). The deep and intermediate layers of the lamina propria connect the body and cover and serve as a transition between the two. The free motion represented by this wave may be diminished by all kinds of adhesions between the superficial mucosa and ligament resulting from several different primary and secondary pathologies (such as chronic inflammation). The adhesions increase the stiffness of the fold and limit its movement. In clinical consultation we try to observe the transverse movement of the muscular body of the

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FIG. 1. Schematic presentation of vocal fold vibration. Left column: frontal section; right column: view from above. (Reproduced with permission (120).)

vocal fold and the vertical wave motion of the mucosal cover. STROBOSCOPIC SEMIOLOGY This semiology has benefitted enormously from the very specialized work of Drs. Cornut and Bouchayer (13) of Lyon. Conditions for successful evaluation of the glottic wave include comfortable phonatory intensity; fundamental frequencies that provide an optimal view of the vocal folds; the v o w e l / i / f o r low frequency phonations; use of the

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patient's habitual speaking Fo. (High frequencies and head voice are associated with low vibratory amplitude and therefore should be avoided.) Characteristic phenomena to be observed include the vibratory amplitude of the glottic wave, which provides insight into the flexibility of the mucosa and its freedom from the underlying body of the vocal fold. Mucosal flexibility is associated with a clear voice and rich resonance. Specific aspects of importance are amplitude of the opening phase; amplitude of the closing phase; bilateral symmetry of these amplitudes; diminution of the opening phase; diminution of the closing phase; variability with phonatory frequency or intensity; and phase delay of wave activity when comparing the two folds. Abnormal stiffness of the glottic wave is also important, and may present in several ways: complete and permanent stiffness on the whole length of the fold (unilateral or bilateral); permanent stiffness on part of the vocal fold (one-third or two-thirds of the

FIG. 3. Bilat, epidermoid cysts in a M-year-old woman.

fold unilateral or bilateral); and vibratory "escape" on a localized part on the opening phase or the closing phase. The permanence of the "escape" may vary with frequency or intensity.

Differential Diagnosis The differential diagnosis rests on four criteria: flexibility of the glottic wave; glottic shape; acoustic qualities of the voice; and history of the dysphonia.

Stroboscopic Findings

FIG. 2. Bilat. sulcus-vergeture in a 44-year-old man.

Clinicians using the stroboscope must be able to relate the vibratory pattern to the anatomical configuration and to the pathophysiology of the disorder. This requires interpreting the stroboscopic recordings relative to normal expectations. The following details the major stroboscopic findings. Static vocal fold concavity, unilateral or bilateral, may be apparent with diminished closing phase; oval glottic shape; slight veiled timbre, absence of richness; slightly diminished intensity; and occasionally difficulties maintaining a sufficiently wide Journal of Voice, Vol. 6, No. 2, 1992

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vocal scale, correct timbre, or intensity appropriate to the setting. Note that this concavity suggests either a bilateral or unilateral glottic sulcus of the open cyst type, whose pathogenesis is congenital. There may eventually be a localized or extended vergeture or mini-vergeture (stria) (33, Fig. 2). A localized bulge may be well delimited at the upper part of the free border of the vocal fold. It may have more or less transparency than the surrounding tissue. The bulge may be accompanied by diffuse inflammation; arborescent capillary dilation or longitudinal dilatation; stroboscopic manifestations of stiffness or significant decrease of vibratory amplitude or decrease of the opening phase of a small localized segment (e.g., adynamic segment); permanent wheezy or hoarse timbre with bitonality; decreased vocal frequency range; strong or weak vocal intensity; and a long history of vocal difficulty (perhaps hereditary problems), which argues more for an intracordal epidermoid cyst (Fig. 3). In contrast, recent infection with sudden and persistent acoustic and resonance changes implies a submucosal cyst with less vascularization. Note that, according to Cornut and Bouchayer, retentional mucous cysts are often anterior or more subglottic. Furthermore, several aspects of the disorder termed monocorditis often mask a congenital ipsilateral or contralateral subjacent lesion, although dysfunction may be associated with a particular effort. This clinical term should be replaced by one based on the associated pathology. Bulging of the free margin of the vocal fold may be associated with stroboscopic evidence of flexibility and a complete disappearance of the bulge during the opening phase; a glottal hourglass shape during phonation; and variations of timbre for certain pitches and intensities. Note that total disappearance of the bulge during the opening phase suggests a fusiform edema, or nodules. A more translucent bulge that does not completely disappear during opening phase suggests a pseudocyst. If the bulge is sufficiently voluminous, it may diminish the stroboscopic amplitude, as in the case of large polyps. A blunt anterior commissure with radiating vascularization associated with slight glottic gap on phonation, other pathologies (including, according to Cornut and Bouchayer, nodules and pseudocysts), diminished stroboscopic flexibility of the anterior-most quarter of the vocal fold. This should arouse suspicion of an anterior or subcommissural microcongenital web. The web may provide some Journal of Voice, Vol. 6, No. 2, 1992

explanation for the hyperfunctional laryngeal tension. In pseudomyxoma and Reinke's edema, the myxoid material generates a massive inertia. Surgical intervention is rarely an urgent issue in any of the nonmalignant pathologies described previously. Malignant tumors often show superficial inflammatory changes or hyperplasia with keratosis or moderate to severe dysplasia. In these cases stroboscopy shows a major and localized mucosal stiffness, which is an urgent signal for biopsy and histological evaluation before radiotherapy or surgery. Laryngeal paresis (flaccid) results in a loss of muscle tone of the affected side. This implies decreased stiffness of the vocal fold body, which makes the entire vocal fold operate mechanically as a single structure because the body is as flaccid as the cover. The vibratory pattern of such a relaxed vocal fold is characterized by wide undulating motions (like the fluttering of a flag) and, as Kitzing has noted, by marked reduction or absence of the mucosal wave. After successful vocal fold augmentation there is generally acoustic and functional indication of improvement in the glottic closure, even if the stroboscopic evidence does not suggest complete recovery. Vascular or capillary ectasia that seem to be isoo lated call for an examination to show possible subjacent pathology (intracordal cyst, nodule, microweb). Occasionally these isolated ectasia show substantial change in the stroboscopic movement pattern. They may be part of the class of constitutional vascular fragility and may respond to medical or behavioral phoniatric treatment. Follow-up stroboscopic examination allows precise evaluation of the healing of the mucosa, particularly in its depiction of the freedom of the mucosal wave. However, inflammation that follows surgical procedures, even after 7-8 days of complete vocal rest, restricts glottic flexibility as observed stroboscopically. Recovery of the glottic wave may not be apparent until as late as the third postoperative month. Many phoniatrists note a failure of glottic wave recovery, or diminished vibratory amplitude after laser procedures. This may also be the case after excessive surgical removal of lesions, which leaves a tissue defect that may extend as far as the vocal ligament. Ventricular fold phonation may present with a distinct stroboscopic picture. The ventricular folds may be seen to approximate but not actually vi-

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brate; they may be seen to approximate and to vibrate; and they may be seen to adduct and though not approximated show clear signs of vibration; and occasionally they may be seen to adduct and interact to produce sound, as in some cases of so-called hyperphonia. In some cases the ventricular folds are the primary sound source. Isolated small stroboscopic asymmetries that coincide with partial changes in vocal register or that occur at specific frequencies within the vocal range disappear after a few sessions of functional therapy. The effect is produced by relaxation of the laryngeal suspensory musculature, which modifies the forces on the larynx and the mass of the vocal folds, permitting better acoustic functioning that can be visualized stroboscopically. We have abandoned the terms hyperfunctional and hypofunctional in describing voice disorders. We believe that they frequently represent cordal pathology (often congenital) or compensation for an isolated difficulty that can be rehabilitated. Stroboscopic study of the v o w e l s / i / a n d / e / a t several frequencies produced in ascending and descending scales and at different intensities may confirm or eliminate suspicions of vocal pathology. FUTURE CLINICAL POSSIBILITIES Laryngeal stroboscopy has come a long way in the past 100 years (1-255), yet there are still many desirable improvements. In the near future we could imagine the following improvements and developments for stroboscopic generators: 1. Standardization of intensity level, frequency level, and phase indications. These data will also appear on the screen of any associated video system. 2. Greater light intensity to allow better use of flexible fiberscopes. 3. Standardization of video systems (maintaining color fidelity during stroboscopy; having high fidelity audio recording and reproduction; and having colored video printing of specific sequences such as inspiration and one cycle of vibration at normal pitch and loudness). 4. Providing the possibility of obtaining precise millimetric measures from the video screen or video print. 5. Simultaneous stroboscopy and kymography (Gross and Schultz-Coulon) so as to obtain more precise quantitative measures.

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6. Coupling of stroboscopy to inexpensive sound spectrographic analysis; electroglottography; and frequency and intensity analysis with paper printout for clinical records. 7. Higher video frame rate recordings. Having achieved these enhancements, stroboscopy may well be considered the best all-around clinical laryngological diagnostic procedure. REFERENCES 1. Timcke R. Die synchron-stroboskopie von menschlichen stimmlippen bzw. ahnlichen schaUquellen und messung der offungszeit. Z Laryngol Rhinol 1956;35:331-5. 2. Schonharl E. Die stroboskopie in der pratischen laryngologie. Stuttgart, Germany: Georg Thieme Verlag, 1960. 3. Perello J. Exploracion audiofoniatrica. Barcelona. Editorial cientifico, 1980. 4. Pascher W, Homoth R, Kruse G. Verbesserung der visuellen diagnostik in der laryngologie und phoniatrie. H N O 1971 ;19:373-5. 5. Seidner W, Wendler J, Halbedl G. Mikrostroboskopie. Folia Phoniatr 1972;24:81-5. 6. Padovan IF, Christman NT, Hamilton LH, Darling RJ. Indirect microlaryngostroboscopy. Laryngoscope 1973;83: 2033-41. 7. Saito S. Microchirurgie stroboscopique du larynx. Rev Laryngol 1973;94:9-10. 8. Wendler J, Seidner W, Halbedl G, Schaaf G. Telemikrostroboskopie. Folia Phoniatr 1973;25:281-7. 9. Kittel G. Farb-video-stroboskopie. Demonstration, 52, Jahrestag. Dtsch. Ges. Sprach-U. Stimmheilk., 1977. Bad Reichenhall, Germany. 10. Hirano M. In proceedings of conference on the assessment of vocal pathology. American Speech and Hearing Association, report 11, 1981:69. 11. Schonharl E. Significance of laryngostroboscopy for practicing otorhinolaryngologist. Laryngol Rhinol Otol 1952;31: 383-6. 12. Smith S. Le jet d'air relatif aux mouvements des cordes vocales des deux modetes. J Fr Orl 1959;8:113-8. 13. Cornut G, Bouchayer M. Apport de la microchirurgie endolaryngee dans le traitement des troubles vocaus. J Med (Lyon) 1971:15-25. 14. Cornut G, Bouchayer M. Indications phoniatriques de la microchirurgie laryngee. J Fr Orl 1972;22:5-52. 15. Cornut G, Bouchayer M. Apport de la microchirurgie laryngee dans le traitement du nodule de la corde vocale. Folia Phoniatr 1973;24:431-7. 16. Cornut G, Bouchayer M. Indications phoniatriques et resultats fonctionnels de la microchirurgie laryngee. Bull Audiophonol 1977;7:5-51. 17. Cornut G, Bouchayer M. Les therapeutiques phoniatriques de la voix chantee. Rev Laryngol 1985;106:289-94. 18. Kitzing P. Photo and electroglottographicalrecording of the laryngeal vibratory pattern during different registers. Folia Phoniatr 1982;34:234-41. 19. Alberti PW. The diagnostic role of laryngeal stroboscopy. Otolaryngol Clin North A m 1978;11:237-54. 20. Arndt HJ. Stroboskopische Diagnostik. Sprache Stime Gehor 1986;10:81-2. 21. Baer T. Measurement of vibration patterns of excised larynxes. QPR 1973;110:169-75. 22. Bartell TH, Bless DM, Ford CN. Stroboscopic examination Journal of Voice, Vol. 6, No. 2, 1992

144

23. 24. 25.

26. 27. 28.

29. 30. 31. 32. 33.

34. 35. 36. 37. 38. 39. 40. 41.

42.

43. 44. 45. 46. 47. 48. 49.

M . - A . F A U R E A N D A. M U L L E R of voice: a comparison of two procedures. Proceedings o f the International Conference on Voice, Vol. II. Kurume, Japan, 1986:15-9. Barth V. Die Lupenstroboskopie. H N O 1977;25:35. Barth V, Pilorget J. La stroboscopie laryngee. Rev Laryngol Otol Rhinol (Bord) 1983;104:359-64. Barth V. Erkennung von minimalen organischen Veranderrungen dutch Einsetzen von bildvergroBernden Verfahren mit Hilfe der Lupenstroboskopie. Proceedings o f the Thirteenth Congress o f the UEP. Vienna, 1986:56. Beck J, Schonhaerl E. Ein neues mikrophongesteuretes Lichtblitz-Stroboskop. H N O 1954;4:449-52. Beck J, Schoenhaerl E. The significance of stroboscopy for the diagnosis of functional voice disorders. Arch Ohr Nas Kehlkopfheilk 1959;175:449-52. Bekbulatov GT. Stroboskopiia v otsenke funksional'nugo vosstanovleniia golosovogo apparata posle operatsii na golosovykh sladkakh. Vestn Otorinolaringol 1969;31: 52-4. Bless DM, Hirano M, Feder RJ. Videostroboscopic evaluation of the larynx. Ear Nose Throat 1987;66:48-58. Bouchayer M, Cornut G. Kystes et pseudo-kystes de la corde vocale, apropos de 32 cas. In: La Voix humaine et ses troubles. Soc Fr ORL 1974:154-8. Bouchayer M, Cornut G. Le sulcus glottidis. Notions nouvelles apportees par la michrochirurgie laryngee. A propos de 31 cas. Cah ORL 1978;13:769-77. Bouchayer M, Cornut G. Les vergetures des cordes vocales. Rev Laryngol 1984;105:421-3. Bouchayer M, Cornut G, Witzig E, Loire R, Roch JB, Bastian R. Epidermoid cysts, sulci and musoci bridges of the true vocal cord: a report of 157 cases. Laryngoscope 1985; 95:1087-94. Brewer DW, McCall G. Visible laryngeal changes during voice therapy: fiberoptic study. Ann Otol Rhinol Laryngol 1974;83:423-7. Cammann RJ, Pahn J, Rother U. Diagnostik der N.laryngeus-superior-Parese. Folia Phoniatr (Basel) 1976;28: 349-53. Catalano G, Rossi MM, Y Bisceglie P. Clin ORL 1963;15: 197. Chaplin VL, Iakovleva II. Stroboskipiia detei kapelly mal' chikov. Nov Med Tekhn 1964;2:41-4. Childers DG. Laryngeal pathology detection. CRC Crit Rev Bioeng 1977;2:375. Colton RH, Brewer DW, Rothenberg M. Evaluating vocal fold function. J Otolaryngol 1983;12:291-4. Cornut G, Lafon JC. Vibrations neuro-musculaires des cordes vocales et theories de la phonation. J Fr ORL 1960; 9:317-24. Cornut G, Bouchayer M, Witzig E. Indications phoniatriques et resultats fonctionnels de la microchirurgie laryngee chez l'enfant et l'adolescent. Bull Audiophonol 1984; 17:473-96. Cornut G, Bouchayer M, Witzig E, Roch JE, Laire R. Diagnostic et traitement du kyste muqueux par retention de la corde vocale, a p r o p o s de 36 cas. Bull Audiophonol 1985; 1:263-74. Cornut G, Bouchayer M, Parent F. Value of videostroboscopy in indicating phonosurgery. Acta Otorhinolaryngol Belg 1986;40:436-42. Croft TA. Failure of visual estimation of motion under strobe. Nature 1971 ;231:397. Cvejic D, Spalajkovic M. Srp Arh Celok Lek 1964;27:751. Damste H. Practica ORL 1957;19:438. Damste H, Huizinga E. Practica ORL 1959;21:349. Damste H. Folia Phoniatr 1968;20:65. Darasovenau C, Popoviciu L. Cesk Otolaryngol 1968;16: 285.

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50. Dunker E, Schlobhauer B. UnregelmafSige Stimmlippenschwingungen bei funktionellen Stimmstorungen. Z Laryngol Rhinol 1961;40:917-34. 51. Eigler G, Podzubwit G, Weiland H. Ein neues mikrophongesteuertes Lichtblitz-Stroboskop zur Beobachtung von Stimmlippenschwingungen. Z Laryngol Rhinol 1953; 32:40-5. 52. Eliseyeva LP, Trinos LA. Mobility of true vocal cords in deaf people and in people with low hearing acuity. Ushn Nos Gorl Bolezn 1972;2:25-8. 53. Ernst R. Stroboscopic studies in professional speakers. H N O 1960;8:170--4. 54. Ernst R. The stroboscopic recognition of functional voice disorders by means of singing and speaking stress. Arch Ohr Nas Kehlkopfheilk 1959;175:452-5. 55. Ertt E, Stein L. History of motorless laryngostroboscopy. Monatsschr Ohrenheilk 1936;70:1463-4. 56. Farnsworth DM. High speech motion pictures of human vocal cords. Bell Telephone Laboratories, 1940. 57. Farr J, Silveria R. Trans Pacific Coast. Oto-Soc 1961:309. 58. Ferrein A. De la formation de la voix de l'homme. Hist Acad R Sci 1900;1741:409-32. 59. Fex S. Judging the movements of vocal cords in larynx paralysis. Acta Otolaryngol (Stockh) 1970;263:82-3. 60. Fex S, Elmquist D. Endemic recurrent laryngeal nerve paresis. Correlation between EMG and stroboscopic findings. Acta Otolaryngol (Stockh) 1973;75:368-9. 61. Fex S. Experimental reinnervation av skelettmeskel och dess tillampning vid larynxpareser [Doctoral dissertation]. Lund, Sweden: 1970. 62. Fex S, Elmquist D. Endemic recurrent laryngeal nerve paresis. Acta Otolaryngol 1973;75:368-9. 63. Flanagan JL, Ishizaka K. Computer model to characterize the air volume displaced by the vibrating vocal cords. J Acoust Soc A m 1978;63:1559-65. 64. Franck F. Optics in phoniatrics. Postgraduate course, 13th Congress of the UEP, Vienna, 1986. 65. Frint T, Kelemen A. Inspiratorische stimmbildung psychogenen ursprunges. Folia Phoniatr 1969;21:105-11. 66. Frint T. Experimentelle untersuchungen seltener stimmphanomene bei einem fall von spastischer dysphonie. Folia Phoniatr 1974;26:422-7. 67. Fulgenicio MS. Laryngeal stroboscopy. A M B 1978;24: 17-8. 68. Gall V. Strip kymography of the glottis. Arch Otorhinolaryngol 1984;240:287-93. 69. Gerull G, Gesen M, Mrowinski D, Rudolph N. Laryngeal stroboscopy using a scanning microphone. H N O 1972;20: 369. 70. Gould WJ, Kojima H, Lambiase A. A technique for stroboscopic examination of the vocal folds using fiberoptics. Arch Otolaryngol 1979;105:285. 71. Gould WJ. The clinical voice laboratory-clinical application of voice research. Ann Otol Rhinol Laryngol 1984;93:34650. 72. Greiner GF, Billenschneider E, Conraux C. Stroboscopic and sonographic aspects of the traumatic larynx. J Fr Otorhinolaryngol 1968;17:237-41. 73. Hirano M, Kakita Y, Ohmani K, Kurita S. Structure and mechanical properties of the vocal fold. In: Lass NJ, ed. Speech and language. Advances in basic research and practice. New York: Academic, 1982:271-97. 74. Hirano M. Morphological structure of the vocal cord as a vibrator and its variations. Folia Phoniatr 1974;26:8%94. 75. Hollien H, Curtis J. J Speech Hear Disord 1960;3:361. 76. Hollien H. Proceedings o f the 5th International Congress Sc. Munich, 1964:362. 77. Hollien H, Coleman R, Moore P. Stroboscopic lami-

STROBOSCOP Y

78. 79. 80.

81. 82. 83. 84. 85. 86.

87. 88. 89. 90. 91.

92. 93. 94. 95. 96. 97. 98. 99. 100. 101. 102. 103. 104.

nagraphy of the larynx during phonation. Acta Otolaryngol (Stockh) 1968;65:209-51. Honjo I, Isshiki N. Laryngoscopic and voice characteristics of aged persons. Arch Otolaryngol 1980;106:149-50. Husson R. Principal facts of vocal physiology and pathology gained by laryngostroboscopy. Rev Laryngol Otol Rhinol 1936;57:1132-45. Husson R. Stroboscopic study of reflex modifications of vibration of vocal cords produced by experimental stimulations of auditory and trigeminal nerves. Compt Rend Acad Sci 1951;232:1247-9. Ishikawa T. Clinical investigation of vocal cord paralysis. Jpn Pract Otol Kyoto 1983;76(suppl):747-52. Ishizaka K, Isshiki N. Computer simulation of pathological vocal cord vibration. J Acoust Soc Am 1976;60:1193--8. Kallen LA. Laryngostroboscopy in the practice of otolaryngotogy. Arch Otolaryngol 1932;16:791-807. Kallen LA, Polin HS. A physiological stroboscope. Science 1934;80:592. Kiowa S. Anesthesia for new functional laryngeal microsurgery with droperidol and fentanyl. Jpn Anesth 1973;22: 545-52. Kirikae I. Uber den Bewegungsvorgang an den Stimmlippen und die Offnungs-Und Verschlubzeit der Stimmritze wahrend der Phonation. J Otolaryngol (Japan) 1943;49: 236--62. Kittel G. Lupen-Mikro-TV-Farbstroboskopie mit Amplituden-bestimmungsmoglichkeiten. HNO 1978;26:94---6. Kitzing P. Stroboscopy--a pertinent laryngological examination. Otolaryngology 1985;14:151-75. Kleinsasser O. Arch Heilk. HNO 1962;180:724. Kleinsasser O. Microlaringoscopia y microcirugia endolaringea. Barcelona: Cientifico-Medica, 1968. Kobayashi S. Glottal vibration after Hirano's reconstruction following hemilaryngestomy. An ultra-high speed cinematographic investigation. Otologia Fukuoka (Japan) 1978;24:831--49. Koeppen K. Quantitative untersuchungen zur klinischen wertigkeit stroboskopischer. Berlin: Befunde Med Diss A, 1988. Koike Y. Application of some acoustic measures for the evaluation of laryngeal dysfunction. Studia Phonologica 1973 ;7:17-23. Koike Y. Diagnosis of voice disorders. Nippon Jibiinkoka Gakkai Kaiho 1979;82:1434-7. Koike Y, Daito N, Imaizumi S. Analisis cuantitativo de las vibraciones de los replieques vocales mediante cineestroboscopia. Rev Logop Fon Audiol 1987;7:126-30. Krahulec I. Importance of stroboscopy in laryngology. Cesk Otolaryngol 1970;19:29-31. Krahulec I, Skrovanek A, Kostolansky P. Cesk Otolaryngol 1970;19:44. Kristensen HK, Zilstorff-Pedersen K. Synchrono-electrostroboscopie examination of the vocal cords. Nord Med 1982;68:927-9. Kruse E. Stroboscopic diagnosis and differential diagnosis of organically caused dysphonia. Proceedings of the 15th UEP Congress. Erlangen, 1988 (in press). Kume M. Microcirugia estroboscopica de la laringe. Rev Med lnst Mex Seguro Soc 1975;14:20-5. Lafon JC. L'impulsion acoustique, unite de phonation et d'audition. LVIe Congress Fr. D'ORL. Paris: Arnette, 1959:248. Landeau M. La Voix (Paris) Maloine 1953. Leden HV. The electronic synchron-stroboscope. Ann Otolaryngol 1961 ;70:881-93. Leden HV, Moore P, Timcke R. Laryngeal vibration: measurements of the glottic wave. Arch Otolaryngol 1960;71: 16-35.

145

105. Leito FB, Morganti AP, Elisabetscky M, Mantoanelli JB. Stroboscopy control of phonetic sound before and after tracheal intubation. Rev Bras Anesthesiol 1968;18:182-91. 106. LoebeU H. Zeit, Hals N. O. Heilk, 1926;15:371. 107. Luchsinger R. Practica ORL 1946;8:436. 108. Luchsinger R. Stroboscopic symptomatology. Pract Otorhinolaryngol 1948;10:209-14. 109. Luchsinger R, Arnold GE. Handbuch der stimmund sprachheilkunde. New York: Aufl. Springer, 1970. 110. Luchsinger R, Nielsen E. Folia Phoniatr 1961;13:93. 111. Luchsinger R, Turetschek G. Folia Phoniatr 1950;2:5. 112. Luchsinger R. Registriering des Klangfarbensechsels Im Niveau Der Stimmlippenebene. Folia Phoniatr 1973;25: 416-23. 113. Grey P. Microlaryngo stroboscopy and "singers nodes." J Otolaryngol Soc Aust 1973;3/4:525-7. 114. Haas E, Bildstein P. Die bedeutung der stroboskopie fur die fruherkennung des stimmlippenkrebses. Laryngol Rhinol Otolaryngol Grenzgeb 1974;53:169-72. 115. Haas E. Heiserkeit und Kehlkopfkrebs. Therapiewoehe 1974;24:5628-32. 116. Hala B, Honnty L. Cinematography of vocal cords by means of stroboscope and great speed. Otolaryngol Slav 1931;3:1-12. 117. Halbedl G. Grundlagen der Technik der Kehlfopf-stroboskopie; in Hb. Med. Elektronik, Tell II, VEB Technik, Berfin, 1964. 118. Halbedl G. Generatorgesteurte und Stimmgesteuerte laryngo stroboskopie. Med Techn (Berlin) 1973 ;13/B 1: 1923. 119. Heinemann M. Kinische untersuchungen beim sulcus glottidis. Z Laryngol Rhinol 1969;48:801-7. 120. Hirano M. Clinical examination of voice. New York: Springer-Verlag, 1981. 121. Hirano M, Bless DM. Videostroboscopic evaluation of the larynx. San Diego, CA: Singular Publishing Group, 1992, 122. Hirano M, Hartmann HG. Aspects of videostroboscopy in practice. Proceedings of the 20th 1ALP Congress. Tokyo: Japan, 1986:402. 123. Hirano M, Hibi S, Terasawa R, Fuciu M. Relationship between aerodynamic, vibratory, acoustic and psychoacoustic correlates in dysphonia. J Phonetics 1986;14:44556. 124. Hirano M, Yoshida T, Yoshida Y, Tateishi O. Strobofiberscopic video recording of vocal fold vibration. Ann Otol Rhinol Laryngol 1985 ;94:588-90. 125. Hirano M, Gould WJ, Lambiase A, Kakita Y. Vibratory behavior of the vocal folds in a case with a unilateral polyp. Folia Phoniatr 1981 ;33:275-84. 126. Hirano M, Nozoe I, Shin T, Maeyama T. Vibration of the vocal cords recurrent laryngeal nerve palsy. A stroboscopic investigation. Pract Otolaryngol 1972;65:1037-47. 127. MacKay DM. Fragmentation of binocular fusion in stroboscopic illumination. Nature 1970;227:518. 128. McKelvic GP, North C. Laryngeal strobomicroscope. Lancet 1970;2:503-4. 129. MacKelvie WB. Stroboscope using grid-controlled neon tube, "strobotron." J Laryngol Otolaryngol 1944 ;59:464-5. 130. Malcolm Farquharson I, Anthony JKF. Research techniques in voice pathology. J Laryngol 1970;84:809-17. 131. Matiutin EM. Stroboscopic phenomena in vocal students. Russk Kiln 1980;13:681-91. 132. Marcos J, Pedrosa C. Rev. Medical Hospital gral. Asturias 1969;4:14. 133. Mareev VM, Papshitscky YA. Stroboscopy in hyperplastic and tumour processes of the larynx. Vestn Otorinolaringol 1972;34:71-5. 134. Mareev VM, PapshitsckiiIUA. StroboskopiiaprigiperplasJournal of Voice, Vol. 6, No. 2, 1992

146

135. 136. 137. 138. 139. 140. 141. 142. 143. 144. 145. 146. 147. 148.

149. 150. 151.

152. 153. 154. 155. 156. 157. 158.

M . - A . F A U R E A N D A. M U L L E R ticheskikh i opukhdevykh protsessakh gortani. Vestn Otolaryngol (Japan) 1973;76:495-500. Matsushita H. The vibratory mode of the vocal folds in the excised larynx. Folia Phoniatr 1975;27/1:7-18. Mavlov L, Kehaiov A. Le role des cordes vocales dans la parole scandee et explosive lors de lesions cerebelleuses. Rev Laryngol 1969;90:320-4. Merriman JS. Stroboscopic photography as a research instrument. Res Q Am Assoc Health Phys Ed 1977;48:62831. Mihashi K. Investigations of phonatory function following vertical partial laryngectomy. Otologia Fukuoka (Japan) 1977;23:786-806. Milner M, Brennan PK, Wilberforce CB. Stroboscopic polaroid photography in clinical studies of human locomotion. S Afr Med J 1973;47:948-50. Minnigerode B. The defiguration phenomenon in motion perception and its effect on stroboscopic laryngoscopy. Laryngol Rhinol Otol (Stuttg) 1967;101:33-8. Monday L, Cornut G, Bouchayer M, Roch JB, Loire R. Diagnosis and treatment of intracordal cysts. J Otolaryngol 1981; 10:363-70. Monday L, Cornut G, Bouchayer M, Roch JB. Epidermoid cysts of the vocal cords. Ann Otorhinolaryngol 1983;92: 124-7. Moore DM, Berle S, Hanson DG, Ward PH. Videostroboscopy of the canine larynx. The effects of asymmetric laryngeal tension. Laryngoscope 1987;97:543-53. Morrison MD. A clinical voice laboratory, videotape and stroboscopic instrumentation. Otolaryngol Head Neck Surg 1984;92:487-8. Muller J. Handbuch det Physiologie des Menschen. BD,H. vonder Stimme und Sprache, 1840:133-248. Musehold A. Stroboskopische und photographische studien uber die Stellung der Stimmlippen im Brust und Falsett-Register. Arch Laryngol Rhinolaryngol 1898 ;7:1-21. Noscoe NJ, Bourcin AJ, Brown NJ, Berry RJ. Examination of vocal fold movement by ultra-short pulse X radiography. Br J Radiol 1983;56:641-5. Ocker C, Pascher W, Rohrs M. Investigations of the vibrationmodes of the vocal cords during different registers. Proceedings of the Stockholm Music Acoustics Conference, Vol. 1. Stockholm: Royal Music Institute, 1983:23946. Oertel M. Das Laryngo-Stroboskop und die laryngostroboskopische Unterschung. Arch Laryngol Rhinolaryngol (Berlin) 1825;3:1-5. Oertel MJ. Ueber eine neue leryngostroboscopische Untersuchungsmethode. Munchen Med Wochenschr 1895;42: 233-6. Ohyama M, Ohno I, Fujita T, Adachi K. Surface ultrastructures of the human laryngeal mucosa observation by a newly developed technique of SEM cinematography. Biomed Res (Tokyo) [Suppl] 1981 ;2:273-9. Pakhmileviche AG. Elektonnaia laringostroboskopicheskaia Kartina prinektrorykh. Vestn Otorinolaringol 1981;5: 58-62. Panconcelli G. Folia Otolaryngol 1900:18:101. Panconcelli G. Z Laryngol 1957;36:570. Panconcelli-Calzia G. Zeitlupenaufnahmen und Strobvokinematographie von Vorgangen im Kehlkopf. Z Laryngol Rhinolaryngol 1929;17:394. Panconcelli-Calzia G. Das synchron-stroboskop nach cremer. HNO 1953;4:62. Pantiukhin VP. Novaia model'stroboskopa. Vestn Otorinolaryngol 1954;16:5. Pantiukhin VP. Stroboscopy in patients after laryngectomy. Vestn Otorinolaringol 1961 ;23:69-73.

Journal of Voice, VoL 6, No. 2, 1992

159. Pascher W, Johannsen HS. Angewandte phoniatrie I methodik der stimmuntersuchung. HNO 1975;23:84--90. 160. Pearlman HB. Laryngeal stroboscopy. Ann Otol Rhinol Laryngol 1945;54:159-65. 161. Pedersen MF, Boberg A. Examination of voice function of patients with paralysis of the recurrent nerve. Acta Otolaryngol (Stockh) 1973;75:372-4. 162. Pedersen MF. Electrogtottography compared with synchronized stroboscopy in normal persons. Folia Phoniatr 1977;29:191-9. 163. Pomez J, Fenelon J, Chassaigne M, Dissez A. L'examen phoniatrique chex quelques malades neurologiques. Rev Laryngol Otol Rhinol (Bord) 1969;90:375-83. 164. Powell LS. The laryngo-stroboscope in clinical examination. Eye Ear Nose Throat Mouth 1935;14:265. 165. Powell LS. Laryngostroboscope. Arch Otolaryngol 1934; 19:708-10. 166. Raes J, Lebrun Y, Clement P. Videostroboscopy of the larynx. Acta Otorhinolaryngol Belg 1986;40:421-5. 167. Raisova V. Laryngoskopie in der phoniatrischen praxis. Presented at the proceedings of the 15th UEP Congress, Erlangen, The Netherlands (in press). 168. Rasinger GA, Frank F, Neuwirth-Riedl K, Wascher K, Gajsek M. Erweiterte Einsatzgebietee von flexiblen und starren optiken in der laryngologie. Proceedings of the 13th UEP Congress. Vienna, 1986:46. 169. Remorino A. Anal Fonol Audiol 1955;1:100. 170. Roch JB, Bouchayer M, Cornut G. Le sulcus glottidis. Rev Laryngol 1981;102:333-46. 171. Rohrs M, Pascher W, Ocker C. Untersuchungen ueber das Schwingungsverhalten der Stimmlippen in verschiedenen registerbereichen mit unterschiedlichen stroboskopischen techniken. Folia Phoniatr 1985;37:113-8. 172. Rossi M, Raso DY, Disceglie P. Clin ORL 1968;20:740. 173. Russell GO, Tuttle CH. Color movies of vocal cord action aid in diagnosis. Laryngoscope 1930;40:549-52. 174. Saito S. Microchirurgie stroboscopique du larynx. Rev Laryngol 1973;94:9-10. 175. Saito S, Fukuda H, Kitahara S, Kokawa N. Stroboscopic observation of vocal fold vibration with fiberoptics. Folia Phoniatr 1978;30:241-4. 176. Saito S, Fukuda H, Kitahara S. Functional microsurgery of the larynx. J Jpn Brocho Esophagol Soc 1976;27:8-16. 177. Salivon LG, Kirina NI. Stroboscopy in malignant tumors of the larynx in the post-radiation period. Zh Ushnykh Sovkh Gorlovykh Boleznei (Kiev) 1972;32:74-6. 178. Sawashima M, Hirose H. New laryngoscopic technique by use of fiberoptics. J Acoust Soc Am 1968;43:168-9. 179. Schlosshauer B, Timcke R. Stroboscopic studies in hemilaryngectomized patients. Arch Ohren-Nasen Kehlkopfh 1956;168:404-13. 180. Schonharl E. Stroboscopic study in myxedema. Arch Ohren-Nasen Kehlkopfh 1954;165:633-5. 181. Schonharl E. New stroboscope with automatic regulation of frequency and recent results of its application to study of vocal cord vibrations in dysphonias of various origins. Rev Laryngol [SuppI] 1956;77:476--81. 182. Schuerenberg B. Vibratory patterns of the vocal folds under pathological conditions. Erlangen (in press). 183. Sedlackova E. Stroboscopic data in relation to the development of voice in children. Folia Phonia tr 1981; 13:81-92. 184. Seeman M. Laryngostroboskopische untersuchungen bei eniseitiger recurrensparese. Monatsschr Ohrenheilk 1921; 55:1621-34. 185. Segre R. Vocal nodules as revealed by stroboscope. Valsalva 1933;9:380-9. 186. Segre R, Salvatori JM. Fono Audiologia 1969;15:191. 187. Segre R. Fono Audiologia 1970;16:23.

STROBOSCOPY 188. Shin Y. Clinical and pathological investigations of sulcus vocalis. Otologia Fukuoka 1976;22:819-35. 189. Shaikh A, Bless DM. Preliminary comparison of vocal fold vibration with strobotelescopic and strobofibroscopic examinations. Proceedings o f the International Conference on Voice, Vol. H. Kurume, Japan, 1986:9-14. 190. Siegert C. Bemerkungen zum stroboskopiscehn bild bei kindern. H N O 1972;20:181-4. 191. Silberman HD, Wilf H, Tucker JA. Flexible fiberoptic nasopharyngolaryngoscope. Ann Otol Rhinol Laryngol 1967;85:640-5. 192. Simko S, Szabo L. Die bedeutung der stroboskopie fur die indikation mikrochirurgischer eingriffe an den stimmbandern. Proceedings o f the 15th UEP Congress. Erlangen, Germany, 1988 (in press). 193. Simpson IC. Dysphonia: the organization and working of a dysphonia clinic. Br J Communicative Disorders 1971;6: 70-85. 194. Smith S. Remarks on the physiology of the vibrations of the vocal cords. Folia Phoniatr 1954;6:166-78. 195. Smith S. Chest register versus head register in the membrane cushion model of the vocal cords. Folia Phoniatr 1957;9:32-6. 196. Stelzig G. Schwingungsmuster bei neurologischen grunderkrankungen. Proceedings o f the 15th UEP Congress. Erlangen, Germany, 1988 (in press). 197. Stern H. Rev Laryngol 1933;54:1079. 198. Stern H. Study of larynx and of voice by means of stroboscopic moving picture. Monatsschr Ohrenheilk 1935;69: 648-52. 199. Szentesi DI. Stroboscopic electron mirror microscopy at frequencies up to 100 MHz. J Phys Sci lnstr 1972;5:563-7. 200. Suzuki Y, Saito S, Hayasaki H, Murakami Y. ORL Soc (Japan) 1964;67:752. 201. Tarneaud J. Ann Otolaryngol 1932;1372. 202. Tarneaud J. Study of larynx and of voice by stroboscopy. Clinique (Paris) 1933;28:337-41. 203. Tassini G. Clin ORL 1966;18:443. 204. Tassini G, Pazzaglia PG. Valsalva 1966;42(suppl):67. 205. Timcke R, Leden HV, Moore P. Laryngeal vibrations: measurements of the glottic wave. Arch Otolaryngol 1958; 68:1-49. 206. Tischner H. Vocal cord stroboscopy with automatic adjustment of frequency. Arch Ohren-Nasen Kehlkopfh 1955; 167:524-9. 207. Titze I. Biomechanics and distributed mass models of vocal fold vibration. In: Stevens KN, Hirano M, eds. Vocal fold physiology. Tokyo, Japan: University of Tokyo Press, 1981:245-70. 208. Titze IR, Gallaudet. Comments on the myoelasticaerodynamic theory of phonation. J Speech Hear Res 1980; 23:495-510. 209. Tobin HA. Office fiberoptic laryngeal photography. Otolaryngol Head Neck Surg 1980;88:172-3. 210. Trenque PL, Perrier P. J Fr ORL 1954;3:6. 211. Vallancien B. Le strobophone. Trans soc de Laryngologie des Hopitaux de Paris, 1954. 212. Vallancien B, Didier, Painleve. Ann Otolaryngol 1957;74: 46. 213. Vallancien B. Folia Phoniatr 1968;20:156. 214. VaUancien B. J Fr ORL 1955;3. 215. VaUancien B. Acta ORL lber-Am 1971;22:205. 216. Vallancien B. Le larynx et sa fonction phonatoire. J Fr ORL 1958;7:135. 217. Vallancien B. Progres en exploration fonctionnelle du larynx. J'Fr Otorhinolaryn gol 1972;21:649-62. 218. Vasilenko YS. The significance of individual indices of the vibratory cycle of the vocal folds in the general assessment

219. 220. 221. 222. 223. 224. 225. 226. 227. 228. 229. 230. 231. 232. 233.

234.

235. 236. 237. 238. 239. 240. 241. 242. 243. 244. 245. 246.

147

of the stroboscopic picture. Vestn Otorhinolaringol 1972; 34:63--8. Vasilenko YS, Ivanchenko GF. Microlaryngostroboscopic examination of patients with functional diseases of the larynx. Vestn Otorhinolaryngol 1978;3:69-73. Van Den Berg JW. Myoelastic aerodynamic theory of voice production. J Speech Hear Res 1958;1:227-44. Van Den Berg JW. Physica van de stemvorming [Thesis]. Groningue 1953 et Uebver die Koppelung bei Stimmbildung 1954. Z Phonet 1954;8:281-93. Van Den Berg JW, Zantema JT, Doornenbal JR. On the air resistance and the Bernouilli effect of the human larynx. J Acoust Soc A m 1957;29:626-31. Van Den Berg JW, Tan TS. Donnees noubelles sur la fonction laryngee. J Fr ORL 1959;8:103-11. Van Den Berg JW. Practica ORL 1959;21:355. Voronina EM, Shtumer YF. Strobofaradizator. Z h Ush Nos Gorl Boky 1939;16:258-63. Watanabee H, Shin T, Matsuo K, et al. A new computeranalyzing system for clinical use with the strobovideoscope. Arch Otolaryngol Head Neck Surg 1986;112:978-81. Ward PH, Berci G. Observations on the pathogenesis of chronic non-specific pharyngitis and laryngitis. Laryngoscope 1982;92:1377-82. Weiss D. Z Laryngol Rhinol 1932;22:391. Welsh AR. The practical and economic value of flexible system laryngoscopy. J Laryngol Otol 1982;96:1125-9. Wendler J. Die bedeutung der stimmstarke bei der stroboskopischen untersuchung. Folia Phoniatr 1967;19:73-88. Wendler J. Practical hints for the application of laryngostroboscopy. VEB TuR (Dresden) 1976. Wendler J. Consideraciones sobre una instrumentacion razonnable para el diasgnostico de voz en la practica clinica. Rev. Logop fon Audiol 1988;8:49-53. Wendler J, Koppen K, Fischer S. The validity of stroboscopic data in terms of quantitative measures. Proceedings o f the International Conference on Voice. Kurume, Japan. "La Garanola," Padova, 1986:36--43. Also in Acta Phon Lat 1987;11:7-12. Wendler J, Koppen K, Fischer S, Cebulla M. On the clinical relevance of vibratory parameters in laryngostroboscopy. Proceedings o f the 15th UEP Congress. Erlangen, Germany. Deutscher Arzte Verlag Krln, 1988:217-23. Wendler J, Otto C, Nawka TH. Stroboglottometrie--ein neues Verfahren zur Schwingungsanalyse der stimmlippen. H N O PraMs 1983;8:263-8. Wendler J, Seidner W. Lehrbuch der phoniatrie 2, Aufl. VEB Thieme. Leipzig, Germany, 1987. Wendler J, Seidner W. Methoden und ergebnisse der phonochirurgie. Z Klin Med 1991 ;46:101-3. West R. A view of the larynx through a new stroboscope. J Speech 1935;21:355. White JF, Knight RE. Office videofiberoptic laryngoscopy. Laryngoscope 1984;94:1166-9. Williams GT, Farquharson IM, Anthony JK. Fiberoptic laryngoscopy in the assessment of laryngeal disorders. J Laryngol Otol 1975;89:299-316. Wilson FB, Kudryk WH, Sych JA. The development of flexible fiberoptic video nasendoscopy (FFVN): clinical, teaching, research applications. A S H A 1986;28:25-30. Winckel F. Neuentwicklung eines lichtblitz-stroboskops fur die laryngologie. H N O 1954;4:210. Winckel F. Improved stroboscopic technic for examination. Arch Ohren-Nasen Kehlkopfh 1954;165:582-6. Winckel F. Z Laryngol 1957;36:574. Witton TH. An introduction to the fiberoptic laryngoscope. Can Anesth Soc J 1981;28:475-8. Witzig E, Cornut G, Bouchayer M, Roch JB, Loire R. Etude anatomoclinique et traitement des kystes kepiderJournal of Voice, Vol. 6, No. 2, 1992

148

247.

248. 249. 250.

M.-A. F A U R E A N D A. M U L L E R moides et des sulcus de la corde vocale (a propos de 157 cas), Cah ORL 1983;18:766--80. Witzig E, Cornut G, Bonchayer M, Roch JB, Loire R. Le kyste muqueux par retention de la corde vocale. Serie anatomoclinique de 32 cas. Schweiz. Rundschau Med (PRAXIS) 74, 21:554-7. Yoshida Y, Hirano M, Nakajima T. An improved model of laryngostroboscope. Otolaryngol (Tokyo) 1977;49:663-9. Yoshida Y, Hirano M, Nakajima T. A video-tape recording system for laryngo-stroboscopy. J Jpn Bronchoesophagol Soc 1979;30:1-5. Perello J, Salva Miquel JA. Alteraciones de la voz. Barcelona. Editorial cientifico. 2nd Ed. 1980.

Journal of Voice, Vol. 6, No. 2, 1992

251. Sataloff RT, Spiegel JR, Carroll LM, et al. Strobovideolaryngoscopy in professional voice users: Results and.clinica/value. J. Voice 1987;4:359--64. 252. SataloffRT. Voice: A new subspecialty. Clinical evaluation of the voice. Common diagnoses and treatments. Ear Nose Throat J. 1987;66:7-47. 253. Karnell MP. Synchronized videostroboscopy and electroglottography. J. Voice 1989; 1:68-75. 254. Costamagna D. La videostroboscopie en laryngologie. Medical Thesis in 2 vol. Nice. 1988. 255. Roch JB et al. Synchronisation de la laryngographie avec la stroboscopie des cordes vocales. Bull. Audiophonol. Ann. Sc. Univ. Franche-Comtr. 1990. Vol. VI. N8.5.547-62.