A new method is presented for predicting the floor impact sound of heavy large-span slabs (70-100 m^2). Compared to the conventional Impedance Method, which results in values around 10 dB higher than the measured values, the new method produces values which agree fairly well with measured values. A modified version of the conventional Impedance Method, used to measure floor impact sound and vibration response, was applied at numerous sites where large-span slabs were used. The main revisions are: the inclusion of the frequency dependency of the impedance increment of fixing girders, the adjustment of impedance decrement values according to natural frequency; and the modification of the radiation model.
