Façade noise abatement prediction: New spectrum adaptation terms measured in field in different road and railway traffic conditions

The Façade Acoustic Insulation Index is one of the most disputed parameters for residential and non-residential buildings. The real performance of the façades does not often agree with the calculated one during the design stage. The field measurement sessions are usually carried out using pink noise spectra, as suggested by the International Standards ISO 717-1. In the present paper six mean spectra derived from in field measurements were proposed: urban toads, traffic lights, roundabouts, freeways, Highways, very high speed trains, high speed trains, and low speed trains. The proposed spectra were equalized against acoustic distortion and were used to measure the noise abatements in a terraced house and in a classroom façade. The highest abatements result for spectra with high levels at high frequencies, better absorbed than low ones by façade elements and frames. The spectrum adaptation terms were also calculated both for the standard and the proposed spectra and were used to predict the façade abatements in compliance with EN ISO 12354-3: the values Cj calculated from the proposed spectra provided more reliable results than the terms C and Ctr (ISO 717-1) and represent a useful tool to predict the noise façade abatements.