H.E. von Gierke

after heated and often bitter debates, SIEBENMANN'S opinion finally prevailed, i. e. , a contribution to cochlear lesions due to vibrations of the floor transmitted via bone conduction could not be demonstrated. For one thing, it was hard to see how appreciable amounts of energy could reach the ears in this manner, considering the attenuation that is bound to occur across each of the many joints along the pathway involved. In some older audiological surveys conducted in industry (e. g. , TEMKIN, 1933), groups of workmen were found who displayed signs of apical-turn lesions, i. e. , low-tone hearing losses for air and for bone. Such lesions could not be expected to results from exposure to air-borne sounds because of the low-frequency attenu­ ation of the middle ear. Although WITTMAACK'S explanation, which was frequently invoked in such reports, does no longer appear tenable, such apical-turn lesions could conceivably be caused by bone conduction components of high-intensity noise in the sense of BEKESY (1948). - As far as I am aware of, no newer studies have been conducted in this problem area, and the older experiments and/or surveys were done at times before signal parameters could be precisely controlled or measured. A detailed, critical review of the older studies on the potential contribution of bone-conducted energy to industrial hearing loss and its underlying pathology may be found in Werner (1940) who, incidently, favored SIEBENMANN'S point of VIew.

The observations made by Paracelsus concerning the dose-effect relationship of poison are generally just as applicable to health­ threatening vibration. With regard to kind, intensity, and duration of the vibration, the "dose" is decisive as to whether the conse­ quences are detrimental, unmeaningful, or tolerable with respect to health. This law of nature determines the tasks and goals of those whose aim is to safeguard health. Researchers worldwide have been occupying themselves with this many-faceted question for some time: how mechanical vibration affects the human organism and at what point damage occurs. If prevention in occupational medicine is to succeed, it is most important that the gaps in our present knowledge be closed, for if technical preventive measures are to be effective and preventive means in occupational medicine successful, they must be based on reliable and complete findings. Whenever many independent researchers have worked in a given field for a long period, a comprehensive intermediate as­ sessment is appropriate to evaluate the level achieved and the direction the research is going. In the area of hand-arm vibration, this evaluation has already been carried out, and the response aroused by this particular research report had led to a demand for a comparable evaluation of the research results on whole-body vibration. This report presents clearly and exhaustively the current status of international knowledge, as well as the questions that remain to be answered.