A Study On Emission Limits Of Structure-Borne Noise From Fixture Transmitted Into Room

In this paper, a field investigation was carried out in buildings influenced by the structure-borne noise from fixtures, whose objective was to study the pollution status. In order to get more reasonable Emission Limits of Structure-Borne Noise from Fixture Transmitted into Room (ELSBNFTR), a subjective response experiment was carried out in the laboratory. In this experiment, the original samples (OS) were generated based on the current ELSBNFTR, while the adjusted samples (AS) were based on the proposed ELSBNFTR. Subjects were asked to make comparison between OS and AS on the basis of relative annoyance. As shown in the results, for each compared group, more than 72.0% of subjects chose "OS were more annoying than AS". Moreover, the differences between OS and AS in the aspect of A-weighted levels and loudness were relatively small, but LC-LA and LF of OS were respectively 3.4-4.4 dB and 8.8-10.9 dB higher than those of AS. Attributed to the higher proportion of low frequency noise energy, the spectra of OS were more imbalanced. In that case, the spectra of OS might have a more rumbly character. Compared with the current ELSBNFTR, the proposed ELSBNFTR was more reasonable.The effect of Quality Assessment Index (QAI) on dealing with room noise complaints was also discussed. It is proposed that QAI should be introduced into ELSBNFTR, in order to reduce complaints mainly caused by room noise with an imbalanced spectrum, while structure-borne noise from fixture is still within ELSBNFTR. Besides, it is suggested that difference value of sound pressure levels at each octave band when the fixture turn on and off should be introduced into the evaluation procedure, and 5 dB could be considered as a limit.