Stroboscopy is a technique designed to allow the examiner to gather information on the vibratory nature of the vocal cords. The technique involves the use of a strobe light which is linked to the frequency of the patient's voice. When the patient utters a tone, the light strobes at a frequency that may be either identical to or close to the frequency of the voice detected. Using a frequency that is close to, but not identical to the frequency of the patient's voice, the recording device can produce a set of images which mimic the true cyclical vibration of the vocal cords. This is analogous to the images produced when a video camera records the image of a rotating wheel. Depending upon the speed of rotation of the wheel and the amount of frames per second at which the camera is recording, the spokes on the wheel may actually appeared to be moving backwards. This is an illusion created by the difference in frequency of the rotating wheel compared with the recording speed of the camera.
By using the information from the stroboscopy exam, the examiner can gather information such as the depth of cancer invasion, the presence of scar or stiffness in a vocal cord, or the relative tone of the vocal cords.
