Noise reduction device applied to water dam and use method

The invention relates to the technical field of dam noise reduction, in particular to a noise reduction device applied to a water dam, which comprises a water inlet canal, the front side and the rear side of the water inlet canal are open, the outer side of the water inlet canal is sleeved with a mounting frame, and a blocking net is fixedly mounted on the inner wall of the mounting frame close to the front side; by arranging a blocking net, a scraping plate, a motor and a reciprocating lead screw, in the advancing process of water flow, the blocking net is used for blocking sundries in the water flow, and in the blocking process, the motor can be driven to drive the reciprocating lead screw to rotate, the reciprocating lead screw drives a movable block to repeatedly move left and right, and the movable block drives the scraping plate to repeatedly move; sundries blocked by the front side of the blocking net are pushed through the scraping plate, so that the sundries move to the edge of the dam, workers can c