A noise suppressing device attachable to a wall within a liquid container can lessen and absorb noise generated by a liquid as it moves within the container. The device has a main plate body with an upper plate surface and a lower plate surface, through holes extending through the upper and lower plate surfaces for permitting flow of the liquid from one side of the main plate body to the other side of the main plate body, and projections formed on the main plate body. Each projection has a base and a tip, and is tapered from the base to the tip. The noise suppressing device also has an attachment device for attaching the main plate body to the container wall. The device is easy to manufacture and install, and effectively suppresses liquid noise.