1. Dynamic laryngoscopy

Dynamic laryngoscope, also called stroboscopic laryngoscope, is mainly used to observe the vibration characteristics of the vocal cords during vocalization. It is the only one that can see the movement of the vocal cord mucosa waves. It can observe the vibration laws of the vocal cords, and provides an objective basis for the diagnosis of vocal cord diseases (such as vocal cord cysts, early vocal cord cancer) and the comparison of vocal cord surgery before and after surgery. With the advancement of electronic technology, the analysis of the image of the dynamic laryngoscope through electronic computers has been realized, so that the subjective factors are more excluded from the dynamic laryngoscope examination, and the development is quantitative. Therefore, dynamic laryngoscopy is of great significance in the fields of laryngology, voice medicine and art noise medicine.

(1) Principle The frequency of human vocalization is higher, and the vocal cords vibrate faster. It is difficult for the naked eye to observe the true situation of the vocal cords vibration. Therefore, in order to observe the real situation of the vocal cord vibration in detail, a certain method is needed to make the rapid vibration of the vocal cord slow down relatively. This method is a dynamic laryngoscope inspection method. The basic principle of dynamic laryngoscope is: ① When a fast-moving high-frequency wave is filtered by a low-frequency scintillation wave, the fast-moving high-frequency wave will become a slow, moving waveform, which is easy to observe. ② Talbot's law: The human eye perceives a continuous dynamic picture for a series of images with a time interval of less than 0.2 seconds.

(2) Inspection method The inspection method of the dynamic laryngoscope is basically the same as that of the straight tube magnifying laryngoscope. The difference is that the light source is an intermittent flash light source, that is, the straight tube magnifying laryngoscope and the flash light laryngoscope cold light source are connected by optical fibers. The camera system can record the true vibration state of the vocal cords at the eyepiece end of the straight tube magnifying laryngoscope, and then replay through the video to carefully observe the vibration of the vocal cords and the condition of the larynx. According to clinical needs, check the dynamic phase, static phase and the phase of 0 degrees to 360 degrees, the true shape, false sound, low tone, high tone, weak tone, strong tone of the vibration pattern of the vocal cords, and record as needed.

(3) Observation indexes or parameters of dynamic laryngoscope ①Symmetry of vocal cord vibration The symmetry of vocal cord vibration is judged by referring to the phase of the vocal cord opening and closing and the width of the lateral deviation of the vocal cord. If the vocal cords are symmetrical in vibration, they appear to be symmetrical and mirror image of each other; if the movement in a certain phase is asymmetrical, the movement of one side vocal cord is beyond the expected time or the following movement of another vocal cord appears This is an important feature of vocal cord movement. ② The periodic normal vocal cords of the vocal cords vibrate regularly. If the vibration is lost, it means that there is non-periodic vibration. When the dynamic strobe is synchronized with the fundamental frequency, a static picture of the vocal cords is visible. In this synchronized state, if any movement of the vocal cords is visible, it will prompt the aperiodic vibration of the vocal cords. ③ Amplitude of vocal cord vibration The amplitude of vocal cord vibration can reflect the tension of the vocal cord itself, and is an objective index reflecting the effective vibration of the vocal cord. If the vibration of the vocal cords is reduced and the thickness and hardness are increased, the amplitude is reduced; if the tension of the vocal cords is reduced, the amplitude is increased. ④ The changes of vocal cord mucosa waves The changes of mucosal waves directly reflect the histological changes of the vocal cord double vibrating body, so it is a sensitive indicator of no pathological changes in the vocal cords. ⑤ When the glottis is closed, because the vocal cords vibrate extremely fast, the actual closed state of the glottis cannot be determined by ordinary laryngoscope, and can only be determined under dynamic laryngoscope. Various lesions of the vocal cords can cause changes in the vibration pattern of the vocal cords, leading to abnormal vocal function.

(4) The significance of dynamic laryngoscope examination ① The diagnosis of subtle lesions helps to find lesions that are difficult to find under ordinary light sources by observing the mucosal wave conditions, such as vocal fold grooves, tiny cysts in the vocal cords, and vocal cord scars. ②Clarify the scope of the lesion. For lesions at or below the free edge of the vocal cord, such as wide-based polyps, prismatic ridges of the vocal cord, etc., the width of the base of the lesion can be understood by observing the mucosal waves, and the scope of surgical resection can be guided. ③In terms of noise surgery, according to the vocal cord vibration and mucosal wave conditions, it is possible to identify hyperplastic lesions with similar morphology or find changes in the subtle structure of the vocal cords to determine the surgical method. ④Dynamic observation of the progress of the lesion The superficial vocal cord lesion only affects the mucosal wave, and when the lesion develops deeper, it affects both the mucosal wave and the vocal cord vibration.

2. Ultra-high-speed movie photography

Ultra-high-speed movie photography allows more detailed observation of vocal cord vibration. The film produced by ultra-high speed can provide the details of the complex vibration process, frequency and intensity of the vocal cords of each vibration cycle. At the same time, it can also capture the non-verbal larynx functions, such as coughing, crying, laughing, and sputum.

(1) Principles and instruments

The ultra-high-speed throat camera system consists of a xenon lamp, an optical system that can reflect the light of the throat under inspection to the camera, an ultra-high-speed camera, an electronic system for operating the light source and the camera, and a time display The pulse motor and other components.

For ultra-high speed vocal cord vibration shooting, the speed is controlled at 1000 to 5000 frames per second, which is 20 to 30 times faster than the normal vocal cord vibration frequency. If the frequency of the vocal cord vibration is 125 Hz when someone makes a sound, the speed of the camera should be 3000 frames per second, that is, about 25 frames of image should be taken every vibration period. When this vibration mode is shown at a normal speed of 24 frames per second, the sound of the film is shown very slowly, and the projected image is also enlarged 125 times. It is beneficial that the sound signal can also be recorded on the film at the same time, in order to compare the sound and the vocal cord vibration image.

(2) Application

Due to the high cost and the time-consuming process of data accumulation, the ultra-high-speed larynx photography system cannot be operated on some patients, and the examination cost is also high. It determines that it cannot be widely used in clinical practice, but in acoustic research and teaching, High-speed photography is quite useful. Although ultra-high-speed photographic examination is not suitable as a conventional method for diagnosing voice disorders, it can provide the number of opening of the glottis in the vocal cord vibration cycle, and can quantitatively evaluate the vibration of each vocal cord. The vibration characteristics and vibration mechanism have certain value. Because ultra-high-speed photography can record images of vocal cord movement, and can be shown multiple times, the study of the physiological function of the larynx and its abnormal phenomena, the discovery of early larynx lesions, follow-up observation of patients with larynx diseases, and larynx surgery It is of great value to compare before and after.