A vibrating electrode has been developed, with which the microphonics produced at a single point on the cochlear partition can be measured. With this electrode, which can be made to vibrate in any of three orthogonal directions, different places on the cochlear partition were investigated. The basilar membrane is more sensitive to displacement in the radial direction than in the direction perpendicular to its plane. The important question is whether microphonics are produced by a constant stationary displacement or whether they are produced only during the movement of the cochlear partition. With the aid of trapezoidal waves it was possible to show that in a fresh cochlear preparation only the static displacement produces the microphonic voltage. A single displacement of the basilar membrane produces astatic voltage lasting for several seconds. This fact has an important bearing on the energetics of the microphonics.Preliminary experiments suggest that the same technique may be used to investigate the inner parts of the cochlear partition.