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OBJECTIVE/HYPOTHESIS Laser-based three-dimensional (3D) imaging allows realistic visualization and absolute measurement of the vocal folds for comprehensive characterization of the oscillation pattern. STUDY DESIGN Exploratory study with descriptive data analysis in healthy cohort. METHODS The custom-developed miniaturized measuring device is an endoscopic camera-laser setup for stereo triangulation and suitable for in vivo application. The laser projection unit generates a regular laser grid that is projected on the vocal folds and recorded at 4000 fps using a high-speed camera. Recordings are performed during sustained phonation on 10 healthy subjects. RESULTS We present absolute values for the lateral and vertical displacement amplitudes and maximum velocities during opening and closing phase. On average over all study participants, the vertical parameters are at least 50% higher than their lateral counterparts. The mean male/female amplitudes are 0.93 mm/0.80 mm in the lateral and 1.28 mm/1.45 mm in the vertical direction. Only 20% of the healthy subjects displayed slight asymmetries in the lateral direction, but 70% showed significant asymmetries in the vertical component. In only 30% of all subjects, the asymmetry trends matched in the lateral and vertical direction. CONCLUSIONS The study illustrates the additional benefit of 3D imaging: consideration of the vertical component and computation of metric units. New, relevant, and even unexpected information was obtained by the incorporation of the additional vertical dimension. Metric units allow for an absolute evaluation of anatomy and dynamics and therefore enables cross-study comparability. The noninvasive acquisition of quantitative measures for evidence-based medicine has the potential to enhance diagnostic and therapeutic procedures as well as basic medical research. LEVEL OF EVIDENCE 4. Laryngoscope, 128:2367-2374, 2018.

Objectives/Hypothesis In professional classical singing, an even voice quality throughout the entire singing voice range is essential. Transitions between vocal registers (passaggio) are the technically most challenging aspects in classical singing. It is hypothesized that they are most affected by vocal fold mass lesions (VFML). Study Design Cohort study. Methods In this study, the effect of VFML on vocal fold vibration in the passaggio regions was analyzed in four female and three male singers suffering from organic dysphonia. The singers were asked to sing an ascending glissando through the passaggio regions, before and after treatment. The vocal fold vibration was documented with transnasal endoscopic high-speed imaging recordings at 20,000 frames per second, supplemented by synchronized acoustic and electroglottographic recordings. Results Major irregularities were found in the passaggio region of four singers before treatment, whereas the respective phonations below the passaggio were almost regular. In two female singers only the upper, but not the lower passaggio was affected. In all four of these participants, the passaggio region was more regular after treatment. In the remaining three participants, the VFML showed no effect on the passaggio region. However, the singers' ability to reach higher pitches was impaired, but was resolved after treatment. Conclusions The data in this case study strongly suggest that the passaggio region could be affected by VFML, even if phonation outside the passaggio regions is unimpaired. When planning surgical procedures for professional singers, clinical examination protocols should therefore include phonatory tests across the passaggio regions. Level of Evidence 4 Laryngoscope, 127:1392–1401, 2017

Laser-based three-dimensional (3D) imaging allows realistic visualization and absolute measurement of the vocal folds for comprehensive characterization of the oscillation pattern.Exploratory study with descriptive data analysis in healthy cohort.The custom-developed miniaturized measuring device is an endoscopic camera-laser setup for stereo triangulation and suitable for in vivo application. The laser projection unit generates a regular laser grid that is projected on the vocal folds and recorded at 4000 fps using a high-speed camera. Recordings are performed during sustained phonation on 10 healthy subjects.We present absolute values for the lateral and vertical displacement amplitudes and maximum velocities during opening and closing phase. On average over all study participants, the vertical parameters are at least 50% higher than their lateral counterparts. The mean male/female amplitudes are 0.93 mm/0.80 mm in the lateral and 1.28 mm/1.45 mm in the vertical direction. Only 20% of the healthy subjects displayed slight asymmetries in the lateral direction, but 70% showed significant asymmetries in the vertical component. In only 30% of all subjects, the asymmetry trends matched in the lateral and vertical direction.The study illustrates the additional benefit of 3D imaging: consideration of the vertical component and computation of metric units. New, relevant, and even unexpected information was obtained by the incorporation of the additional vertical dimension. Metric units allow for an absolute evaluation of anatomy and dynamics and therefore enables cross-study comparability. The noninvasive acquisition of quantitative measures for evidence-based medicine has the potential to enhance diagnostic and therapeutic procedures as well as basic medical research.4. Laryngoscope, 128:2367-2374, 2018.

Objectives/Hypothesis Quantitative analysis of endoscopic high-speed video recordings of vocal fold vibrations has been growing in importance in recent years. The videos have mainly been analyzed using subjective evaluation, but this is examiner dependent, and the results show inadequate interobserver agreement. The aims of this study were therefore to identify appropriate objective parameters for analyzing high-speed recordings to differentiate healthy voice production from organic disorders. Study Design Methods A total of 152 females were examined, divided into 77 healthy and 75 with four different pathological conditions: laryngeal epithelial thickening, Reinke edema, vocal fold polyps, and vocal fold cysts. Vocal fold vibrations were recorded with a high-speed camera (4,000 Hz, 256 × 256 pixels) during sustained phonation. Parameters computed from the glottal area waveform (GAW) and from phonovibrogram (PVG) were analyzed. Multiparametric linear discriminant analysis was performed to classify pathological conditions versus the healthy group. Results Twenty of 44 parameters were identified that are capable of distinguishing between the individual types of pathology. PVG parameters showed better performance than GAW parameters. Parameters representing vibrational periodicity via standard deviation showed better performance than absolute parameters. In addition, linear discriminant analysis achieved reliable differentiation between healthy and pathological vocal fold vibrations: 72% for the five-class problem (all groups separately) and 88% for the two-class problem (healthy vs. all pathologies taken as one class). Conclusions The study succeeded in defining objective parameters for analyzing endoscopic high-speed videos and suggesting first parameters for differentiation between healthy dynamics and dynamics of organic pathologies. Level of Evidence 3b

In professional classical singing, an even voice quality throughout the entire singing voice range is essential. Transitions between vocal registers (passaggio) are the technically most challenging aspects in classical singing. It is hypothesized that they are most affected by vocal fold mass lesions (VFML).Cohort study.In this study, the effect of VFML on vocal fold vibration in the passaggio regions was analyzed in four female and three male singers suffering from organic dysphonia. The singers were asked to sing an ascending glissando through the passaggio regions, before and after treatment. The vocal fold vibration was documented with transnasal endoscopic high-speed imaging recordings at 20,000 frames per second, supplemented by synchronized acoustic and electroglottographic recordings.Major irregularities were found in the passaggio region of four singers before treatment, whereas the respective phonations below the passaggio were almost regular. In two female singers only the upper, but not the lower passaggio was affected. In all four of these participants, the passaggio region was more regular after treatment. In the remaining three participants, the VFML showed no effect on the passaggio region. However, the singers' ability to reach higher pitches was impaired, but was resolved after treatment.The data in this case study strongly suggest that the passaggio region could be affected by VFML, even if phonation outside the passaggio regions is unimpaired. When planning surgical procedures for professional singers, clinical examination protocols should therefore include phonatory tests across the passaggio regions.4 Laryngoscope, 127:1392-1401, 2017.

Objective/Hypothesis Standard laryngoscopy suffers from a lack of information about the actual size of the observed objects (i.e., vocal fold length and oscillating amplitudes). However, there is much interest in absolute measures for both clinical and research purposes. Therefore, a laser projection device has been developed that enables the precise determination of absolute units in endoscopic investigation during respiration and phonation. Study Design An experimental study in which 9 adults underwent high-speed endoscopy combined with a laser projection device. Methods The projection system consists of two parallel laser beams with a distance of 3.8 mm. It is mounted on the tip of a rigid endoscope, which is attached to a digital high-speed camera. During development and design, examination situations were taken into account. Two laser spots are projected onto the vocal folds and enable the definition of a metric scale within the endoscopic image. Knowledge-based image processing algorithms were used for evaluation. Results First measurements of the vocal fold length during phonation were performed in a group of nine healthy male students. The determination of glottal length during phonation agrees with former results. Quantifying vocal fold velocities in absolute units makes it possible to estimate the initial collision forces. Conclusions The presented laser projection system allows the determination of absolute measures in the larynx. Because of the simple functional principle, the system is open for use without digital high-speed recording as well. Absolute units may also be helpful in voice diagnosis and in monitoring during voice therapy.