Hybrid frequency compensation is provided. The design includes providing a reference object while recording the visual representation of the surgical procedure, scaling the ruler to correspond to the reference object within the visual representation of the surgical procedure, and superimposing the ruler from the scaling on the visual representation for subsequent viewing. When the operation button portion is pressed against the pressing force of the plate spring portion, a button contact portion provided at a front end of the plate spring portion allows the switch to operate. Once this is designated, instances of the types of messages will be identified using the analysis criteria, and then analyzed to determine the desired information.