Study Of Frequency Analysis And Annoyance Due To Noise Sources Of Facilities In Urban Residential Area

Along with the rapid urbanization in China, peoples' living standard is improving and the industrialization is accelerated developing in recent years. The quantity of household appliances and residential area common facilities is stepping up, it results in the gradually increasing of the quantity and intensity of noise sources in urban residential area. And the environmental noise assessment method in existence can not reflect the tangible impact of residential area low frequency noises, in this thesis the research is carried out on the investigation of residential area facility noises, frequency analysis and annoyance experiment in allusion to this conflict, and providing reference material for the adjustment of the environmental noise assessment method in existence.On the basis of literature consult and research actuality, the most typical sound sources from associated facilities in residential area are selected in this study. It is found that there are 12 typical sound sources such as noises from supply electricity systems, underground parking, elevator equipments, supply heat systems, supply water systems, air condition equipments, and ventilation system. By using the sound analysis instrument VS302USB, the noise sources from above associated facilities at normal operation cases have been recorded and examined. Furthermore, the spectrum of these noise sources and the energy ratio among the low, middle and high frequency bands are analyzed by sound signal processing. Results show that the maximum sound pressure level is located in low-frequency bands (9 in 12 typical sound sources) and the energy distribution in low-frequency bands (7 in 12 typical sound sources) is the most. So the low-frequency sounds from associated facilities are the most annoying noise in urban resident area.By using the paired comparison method, 5 low frequency noises and 5intermedia frequency noises are chose for the annoyance experiment. These noises are regulated to same sound pressure levels (4 grades), same A weighted sound pressure levels (4 grades) and same loudness level (4 grades). Furthermore, in order to obtaining the judgment criterions and rules, the single frequency sounds (center frequencies of octave bands between 63 Hz and 8000Hz) and multiple tone sounds (three highest sound pressure level and its frequency of recorded residential area typical facility noises) are regulated to same loudness levels (4 grades) for the annoyance experiment. The experiment results shows that, the annoyance degrees of low frequency noises which are lower in same sound pressure levels and same loudness levels experiment are magnified in same weighted sound pressure levels experiment. So A weighted sound pressure level should be modified when it is applied to assess the low frequency noises, lower the attenuation in low frequency range, and makes the A weighted sound pressure level reflects the tangible impact of low frequency noises.