A method of measuring a biomechanical parameter of soft biological tissue is described. The method includes a pre-measurement process wherein an impulse applying device applies a pre-pressure to a surface of the tissue via an end portion contacting the tissue surface. While maintaining the pre-pressure, the device generates at least two impulses separated by a time interval, each impulse causing the end portion to impart to the tissue an action with certain parameters, each action inducing a response of the tissue. A value of a biomechanical parameter of the tissue is determined from each response induced. A determination is made as to whether the determined values of the biomechanical parameter are sufficiently similar to each other to indicate that the pre-pressure, the parameters of the end portion actions and the time interval are acceptable for use in a measurement process to be conducted on the surface of the tissue.