Evaluation of the soundscape of District 4 of Tabriz metropolis using linear regression model

With the development of sciences and technologies, the growth and expansion of cities led to the destruction of the environment and production of various biological pollutions across human societies. Meanwhile, noise pollution has been one of the types of pollution that has adversely affected the comfort of urban residents and is found to be directly associated with the mental health of people in society. This type of pollution may cause mental diseases, irritability, allergies and other nervous and psychological diseases. This paper aimed to evaluate the noise landscape of District 4 of Tabriz and investigate the amount of this type of pollution in the peak hours of activities in this city, as well as the impacts of social, physical and environmental variables on the urban environment.

This paper used a methodology that combined descriptive-analytical, documentary and survey methods. District 4 of Tabriz was divided into squares of 200*200 m in dimensions, based on a standard square grid, with the center of each square designated as the noise acquisition station. The equivalent continuous sound level (Leq) of each station was measured for 3 minutes at two-time intervals of 8-11 a.m. and 7-10 p.m. in June to December of 2021. Noises were acquired by using a decibel meter device at a sound pressure level of Grid A with a Fast Response Speed. The dependent variable was the equivalent continuous sound level (Leq) at two morning and afternoon time intervals and independent social and physical variables were population density, construction density, the distance from pathway grids, the distance from administrative and police uses, the distance from educational uses, the distance from urban installation and equipment uses, the distance from commercial and service uses, the distance from treatment uses, the distance from industrial uses, the distance from barren land, the distance from green spaces and the distance from aerial corridors. Each of the maps pertaining to the independent and dependent variables of District 4 was separately sketched in GIS software, and then, the effects of each of the independent variables on dependent variables were examined by using a linear regression model in SPSS software.

Surveys indicated that the noise landscape of District 4 of Tabriz Metropolitan consisted of children game noises, noises caused by vehicle and motorcycle traffic, trash trucks when loading trash bins and the sound of construction workers across the neighborhoods, noises caused by motorcycle horns and their swerving noise, the passage of trucks and vans, as well as motor vehicles on the streets and other main axes, the traffic noise of inter-city buses and their horns, load trucks, international transit trucks on first degree axes (Pasdaran Highway and Santou Road), etc. The evaluation of independent social and physical variables with dependent variables (sound equivalent level (Leq) in the two intervals of morning 8 to 11 and evening 19 to 22) shows that out of 12 independent variables of district 4 of Tabriz metropolis in the morning time interval, 9 independent variables of population density , building density, distance from road network, distance from administrative and law enforcement use, distance from urban facilities and equipment use, distance from medical use, distance from industrial use, distance from green space use and in the evening period, 7 independent variables of population density , building density, distance from road network, distance from medical use, distance from industrial use, distance from green space use and distance from air corridor have a significant effect on the sound equivalent level (Leq) and the level of noise pollution in district 4 of Tabriz metropolis. And the variables of distance from administrative and law enforcement use due to the closure of this use in the evening period and commercial and service use despite the high population density of this use but due to the high distribution in the localities of the region, the distance from it do not have an effect on the sound equivalent level (Leq).

Linear regression model results for evaluating independent and dependent variables (equivalent continuous sound level (Leq)) at each time intervals (morning and afternoon time intervals) indicated that the semi-eastern neighborhoods of District 4 suffer from higher noise pollution, while semi-western neighborhoods were dealing with lower amounts of nose pollution.