The article, which consists of several parts, continues the discussion of some bright pages from the history of vestibulology in the 20th century. The third part deals with the impact of the global “otosclerotic boom” and the success of cophosurgery in the 1950s and 1960s on the development of vestibulology. The need to study the vestibular function in patients with otosclerosis was due to the task of determining the stage of the otosclerotic process, assessing the functional state of the inner ear depending on hypo- or hyperreflexia of the labyrinth, predicting the severity of the postoperative vestibular reaction and its objective assessment in the postoperative period. Vestibular studies have helped to comprehend important pathogenetic aspects of otosclerosis: understanding the impact of the otosclerotic process on the structures of the inner ear due to hydrops of intralabyrinthine fluids when the stapes is immobile, through the impact of metabolic products of active foci directly on prescription formations, and others. The article tells about the revival of interest in labyrinthology after the Second World War in the aspect of the study and surgery of otosclerosis. The great interest of Soviet otosurgeons in the pre-war work of Julius Lempert on the fenestration of the labyrinth (1938) and in the successes of world stapedial surgery in the 1950s is reported. The facts are given about the visit of the author of the stapes mobilization operation, Samuel Rosen, in 1958 to the USSR and his participation in the V All-Russian Congress of Otorhinolaryngologists. As a result of these global processes, in 1964, for the improvement and widespread introduction of surgical methods for restoring hearing in patients with otosclerosis, prominent Soviet scientists-otorhinolaryngologists – A. I. Kolomiichenko, K. L. Khilov, S. N. Khechinashvili, N. A. Preobrazhensky and V. F. Nikitina were awarded the Lenin Prize. Among the well-known researchers of otosclerosis are domestic scientists and at the same time successful otosurgeons, women, contemporaries – L. G. Svatko, O. F. Patyakin and N. I. Hrappo. Clinical-morphological-histochemical comparisons and studies of the activity of the otosclerotic process, carried out in the works of the professor of the Kazan Medical University Lyudmila Grigoryevna Svatko, a deep researcher of the pathogenesis of otosclerosis, are reported. It tells about the professor of the Moscow Research Institute of Ear, Throat and Nose Olga Fyodorovna Patyakina-Fyodorova and about the school of domestic otosurgeons she created. The article tells about the long-term studies of the vestibular function in otosclerosis and other diseases by the famous otoneurologist, professor of the Samara Medical University Nina Stepanovna Khrappo and about the audiology direction of the ENT department, for many years headed by Academician I. B. Soldatov. A conclusion is made about the stimulating and beneficial effect of the study of the “mysterious sphinx” (according to N. V. Belogolovy, 1933) and cophosurgery on the development and improvement of vestibulometry techniques, as well as functional ear function studies in general, and more broadly, otosurgery, as such.