The invention relates to a filtering apparatus (15) for filtering an ultrasound signal, which is influenced by an electrical unit and comprises a first part including information about an object (4) from which the ultrasound signal has been received and a second part not comprising information about the object. A correction signal determination unit (17) determines a correction signal being indicative of the influence of the electrical unit on the ultrasound signal from the second part of the ultrasound signal and a correction unit (18) corrects the first part of the ultrasound signal based on the determined correction signal for filtering the influence of the electrical unit out of the ultrasound signal. Since the correction signal is indicative of the influence of the electrical unit, wherein the correction signal is used for correcting the ultrasound signal, unwanted interference visible in the unfiltered ultrasound signal can be filtered out.