This letter describes a simple variable‐delay line which makes use of the well‐known phenomenon of stiffening of a solid caused by piezoelectricity. In a piezoelectric ceramic bar we emit a Lamb wave which generates an electric field perpendicular to the direction of the wave. Short‐circuiting the electric field by joining together certain metal strips placed on one of the two free surfaces of the bar, we obtain a reduction of the velocity dependent on the piezoelectric coupling factor. The delay variation obtained in this way is only 0.013 μsec/mm. However, it can be controlled digitally in quite a simple way by means of an analogical multiplexer. A line of about 70 mm permits a variation of about 1 μsec, which should make it possible to use the device in the field of acoustic visualization for medical diagnostics.