The Sound Environment Of Urban Coastal Spaces In North Cities

As the cities experience fast development,sound environment related issues are attracting more attention.The coastal space is part of the urban public space,and the sound environment has a direct impact on the environment quality of th e coastal space.It is therefore imperative to improve the sound environment of the coastal space in order to enhance the life quality of the residents.Based on the inter-governmental project "China-Croatia study on the evaluation of the acoustic comfort of the non-acoustic space",this paper aims to identify the multi-dimensional evaluation standards on acoustic source perception and sound environment in the urban coastal space,explore the relationship between the urban coastal space and the seascape sound,and reveal the differences in the sound environment between the coastal space and the non-coastal space.This paper first makes a systematic study of the sound environment in the urban coastal space,reviews existing studies on this subject at home and abroad,and identifies the definition and scope of the sound environment in the urban coastal space.The coastal city Huludao in north China is selected as the investigation site and the public space of the inland city Harbin and the Croatian capital Zagreb are selected to make comparative study.On-site measurement and questionnaire survey are made to investigate the sound environment of the urban coastal space and highlight its features.Beginning with the layout and sound environment of the urban coastal space,this study simulates the noise map using Cadna/A software,and design and optimize the sound environment simulation scheme with the orthogonal experiment.An ideal seascape acoustic propagation model that includes 7 planning factors is established to analyze how the environmental factors affect the seascape acoustic propagation,laying foundation for the study of the sound environment of the coastal space.Clarify the sound source composition of urban coastal space.This paper analyzes the features of the acoustic sources,interviewees and physical environment with the statistical method.We have identified factors that affect the perception,comfort and satisfaction of the sound environment and evaluated the sound environment.A cross-cultural and cross-territorial comparison is made to study the differences between the coastal space and the non-coastal space.The BP neural network technology is employed to predict the acoustic comfort of the urban coastal space.The findings suggest that in the coastal space,the acoustic propagation of the seascape is subject to the distance to the sea,the depth of the sea,the building density,the height differences and the openness.Seascape sound,human voice,children's playing sound and music are the dominant sound source of coastal space,and seascape sound can be understood as linear sound source.Analysis on the features of the interviewees reveals significant differences in the acoustic source perception about the coastal space and the non-coastal space.The sound satisfaction is positively correlated to the natural sound and the children's sound in the coastal space,and negatively correlated to the musical sound.In the non-coastal space of Croatia,the human activity sound is negatively correlated to the sound satisfaction.In the coastal space and non-coastal space,the natural sound is positively correlated to the general environment satisfaction.The general environment satisfaction is positively correlated to the sound satisfaction in the coastal space,and negatively correlated to the non-coastal space in Croatia.In the coastal and non-coastal spaces,most acoustic sources are correlated to individual preferences.The purpose of visit is the major factor in both the coastal space and the non-coastal space.The health conditions of the interviewees in the coastal space and non-coastal space are correlated to the general environment satisfaction.The visit frequency and place of residence of the interviewees in the coastal space is correlated to the sound satisfaction,but not in the non-coastal space of Croatia.The educational background of the interviewees in the coastal space and non-coastal space is negatively correlated with the general environmental satisfaction.The preference and annoyance degree perceived by the interviewees about the sound environment is related to the visit frequency,age and place of residence.The visit frequency and purpose are the factor that decides the importance of quietness in the coastal space and non-coastal space.Gender has no significant impacts on the sound environment evaluation both in China and Croatia.The educational background of the interviewees is positively correlated to the quietness demand in the coastal space.In the non-coastal space of Croatia,the age of the interviewees is positively correlated to the quietness demand.Therefore,the functions of and human activities in the urban coastal space should be taken into consideration in the sound environment design.Results from the sound environment evaluation of the urban coastal space show that,apart from the thermal environment,the evaluation results of China's coastal space are inferior to those of the non-coastal space in Croatia." Excited" can be used to evaluate the coastal space.The multi-dimensional evaluation factors of sound environment include 3 factors: liking degree,annoying degree and quiet degree.There are significant differences in the environment indicators and satisfaction evaluation.In the urban coastal space,the acoustic comfo rt is positively related to the general satisfaction.In the subjective satisfaction evaluation of the general environment,the natural conditions,urban conditions and physical environments are the major evaluation factors on the satisfaction about the co astal space and non-coastal space.It is noteworthy that the natural environment is the most important factor in the satisfaction evaluation of non-coastal space in Croatia,which is not the case with the coastal space.The importance of quietness is negatively correlated with the environment satisfaction of coastal space in Croatia.The results indicate that,in the non-coastal space of Croatia,the quiet space is more popular.The acoustic comfort prediction model in the coastal space is built based on th e BP neural network and multiple linear regression,with the social features of the interviewees,the sound environment and related physical environment as the input factors,and the acoustic comfort evaluation results of the interviewees as the output factors.The correlation coefficient between the predicted values of the BP neural network and the actual values is 0.887.The model proves to be effective to predict the acoustic comfort of the coastal space,providing theoretical basis and technical support for the designers to address the issues related to the sound environment of the urban coastal space.