Unterdecke

The invention relates to a false ceiling for buildings which is designed to absorb sound waves and has perforated metal plates, whereby one or several suspended plates are designed so thin that they are capable of vibrating and, together with the hollow cavities above them, form a spring mass system similar to a film absorber, and whereby the lowest metal ceiling has a large number of evenly or unevenly arranged holes with a diameter of 1-3 mm and a hole surface precentage of less than 4 percent.