Evaluation of airborne and impact sound insulation by means of loudness

The currently used evaluation methods in ISO 717 have the possibility of including spectrum adaptation terms, which may have the advantage of improved correlation with subjective evaluation of the sound insulation. However, the current method is complicated, and it is open for many variations in terms of frequency range and spectrum. A new evaluation method is suggested, which is based on the Zwicker loudness calculated from third-octave band measurements according to ISO 532 B. Initial investigations indicate that this new method may be superior to the current ISO 717 methods in terms of correlation with subjective evaluation. According to the procedure for calculation of loudness the third-octave bands below 200 Hz are combined into broader bandwidths, which may be an additional advantage in relation to the measurement uncertainty at low frequencies.