A sound or probe for determining the internal measurements of hollow organs and hollow parts of, for example, humans includes two rod shaped spring elements at the head of the sound which in turn are attached at their one end in an axial direction with their unattached ends spreading apart upon release of tension and with a thread under tensile stress connecting the spring elements and being guided to their base by the sound with means being provided for indicating the actual distance between the ends of the spring elements in accordance with the relative shifting position of the thread and sound.
Sound for insertion in the body for the determination of the internal measurements of hollow organs