Means for suppression of rainfall noise comprises a sheet (12, 22) of flexible plastics material for lamination to e.g. a conservatory roof panel (10, 20). The exposed surface of the sheet (12, 22) has an array of projections such as peaks or domes (14) or ribs (24) of the same order of size as the diameter of heavy raindrops, to break up the drops before completion of impact thereby temporarily spreading generation of noise and reducing the intensity thereof. The sheet may incorporate or be coated with a colour change material, such as a photochromic, thermochromic or electrochromic pigment, ink or dye.