In this paper, we discuss the development of a new noncontact method for determining cylinder configurations using sound phase delay. In order to improve the accuracy of the measurements, the effect of the cavity in which the cylinder is placed has been studied. When the cylinder is placed near a side wall of the cavity, the phase delay angle increases, particularly for cylinders with odd periodic deflection. Thus, by varying the gap between the cylinder and the side wall, it is possible to determine the cylinder configuration even if the deflections are small. We propose a new method, in which the influence of noise is avoided by measuring the noise interference using a pair of microphones in the cavity.