Abstract: An acoustic output of therapeutic devices used in shock wave therapy can be obtained by measuring the pressure waves radiated from the pressure wave transducer in water. Since the pressure waves used in shock wave therapy generate severe bubbles in water, measuring the surface vibrations of the pressure wave transducer using the laser Doppler method includes significant noise caused by the bubbles. This invention utilizes a filter generated to eliminate the noise in the vibration signals measured by the laser Doppler method, which is caused by the bubbles. The filter is generated by comparing the vibration signals measured in degassed distilled water with the reference signals measured in air at the minimum output setting of the shock wave generation device. Using the filter, it is possible to estimate the vibration signals of the pressure wave transducer generated underwater under the set conditions of the specific shock wave generating device.