[Changes in rigidity of the internal ear in body tilt].

We tried to select information concerning changes in acoustic rigidity of the internal ear in 90% body tilt from tympanogram. In such conditions there is no correlation between a 10-fold rise of perilymph pressure and tympanogram parameters. This contradiction suggests that rigidity of tympanogram is a total of rigidity of the ear canal part, middle and internal ear; that inert rigidity of the middle ear in body tilt masks a weak dynamic component of the internal ear. Determination and isolation of the ear canal rigidity from tympanogram (compensation) is a standard procedure. For compensation of the dominating static component of the middle ear we used an original technique -- deduction of the numbered tympanograms. We estimated that deduction of the initial position tympanogram from subsequent tympanograms yields the dynamic component. The procedure of deduction for the tilt angles +75, 60, 45, 30, 15, O, -15 and -30 produced transformed tympanograms (TT) the rigidity of which was 7-10 times less that peak rigidity of standard tympanograms. Peak rigidity of TT of 5 volunteers (n=8) changed as the function of a tilt angle and significantly differed in different positions. TT rigidity may be formed by peripheral cochlear membranes.