In the last few years more and more construction companies have started to project and build wooden houses, some even with more than one floor. However, during the design of the structure they often forget the requirements of ČSN 73 0532, that deals with impact and noise insulation. The problem lies in the fact that, in practice, the only methods used are those to determine the weighted sound reduction values for silicate based structure, while they will fail in a wooden construction. This paper presents a computational procedure for determining the airborne sound reduction of cellular type soffits. When designing or renovating buildings a comprehensive account of all aspects should be given (construction, structural, architectural, financial and others). Nowadays the financial aspect is very crucial and therefore, more and more clients are interested in the energy performance of buildings. However, in terms of comfort of the people living in the interior the aspects of acoustics, lighting and heating are more important.