Proposal of a simplified method for the prediction of impact sound insulation between rooms, from below to above

The impact sound transmission provided by floors is a complex phenomenon that usually includes direct transmission and flanking transmissions. There are, however, situations where impact sound propagates between spaces only by flanking paths, such as those when noise is generated in lower rooms and annoyance is perceived in overlying rooms. This type of transmission can be relevant, for example, in buildings where the commercial space (emitting space) is located on the lower floor and the dwelling (receiving space) is positioned on the upper floor, a typology that is common in countries such as Portugal. In these cases, the quantification of impact sound insulation between rooms is not an easy task. For its accurate prediction, numerical modeling can be employed, using the finite element method, boundary element method or statistical energy analysis (SEA). In the design phase, simple approaches to tackle the problem are usually preferred, such as those described in standard EN 12354-2. Nevertheless, the described situation is not under the scope of this standard and no other simple alternatives are yet available. In the present study, the authors propose a simplified methodology to approach the problem, where empirical formulas are developed, for prediction of flanking sound transmission on heavy weighted building structures. From a large number of experiments and taking into account similar parameters to those defined in the methodologies prescribed in the standard EN 12354-2, a genetic algorithm is used to find out the optimal values that are used to build the simplified expressions.