Sound Field Simulation And Optimization At Shanghai Xing Zhong Road Station

Subway station is a place where congregates a lot of passengers and staffs. Its sound environment is very important for people’s psychological and physical health. The noises generated from subway inbound, outbound and the equipment affect on the acoustical property in the station. Although the subway station is not professional acoustic space, the lack of proper acoustical design may seriously affect the sound quality and the speech intelligibility in the station. A sample station named Xingzhong Road on metro line 9 in Shanghai is considered in this thesis. Sound-field simulation and optimization design of the station is carried out. Furthermore, setting the public address announcement as the sound source, acoustics of the station is analyzed and optimized.Firstly, geometric dimensions of the station are measured, and the noises in the station at different operating conditions of a subway as well as the sounds of the public address system are also measured. The three-dimensional numerical model of the station is established based on the measured geometric data. The noise of the subway train at three cases: coming, stopping and going are measured. Different waiting and seating areas are mainly considered in the measure point arrangements. At the same time, the sound source information is collected when the address announcement is working. After spectral analysis of the sound samples, energy distributions of the station noises are obtained, which will be used in the next acoustical simulation and optimal design of subway station.Secondly, the finite element(FE) models of the station are established and used for simulation, optimization of the sound field. The FE models at two common working conditions of the subway train: coming and going are considered. To prove the correctness of the established model, the sound pressure levels(SPLs) at the measure points are calculated and verified by tests. Optimizing scheme based on the orthogonal experiment algorithm is presented and performed to reduce noise in the station, and simulation is done when the sound-absorbing material attached at different position on the tunnel wall. The best scheme is obtained. The calculating results show that the proposed optimal approach can improve the energy distribution of the sound field and reduce the SPLs effectively.Finally, acoustical design model of the station is established for optimization designs of the sound field in subway station. The optimization process is performed by the simulating calculation and subjective evaluation method. Several sound samples are simulated by changing the sound-absorbing materials attached on the ceiling of the subway station model. Subjective tests of these sounds are conducted by using the paired-comparison method(PCM). We found that people prefer to choose a shorter RT. The relationship between the RTs and the averaged sound absorption ratio of the materials suggests the most suitable RT(MSRT) value of the Xingzhong Road station. The contrastive analysis of the other objective parameters under different RTs gives a further proof of the MSRT. Moreover, the sound absorption treatments are performed on the ceiling and tunnel wall of the station at the same time, and FE model are used for simulation. The calculated SPL show a better sound field quality than the previous one.This thesis is to eatablish an acoustical simulation and optimization procedure of underground subway station, which can be directly applied to other underground subway station. The proposed simulation approach is helpful for improvement of the acoustical environment and can provide technical support for the design of underground subway station.