A preliminary investigation of noise impact within metro stations in the urban city of Guangzhou, China

Evaluation of Building Construction-Induced Noise and Vibration Impact on Residents

Environmental noise and vibration induced by building construction are increasingly prominent in daily life. If the noise and vibration level exceeds the corresponding standard limits stipulated by the country, humans’ normal life, working, or studying efficiency would be interfered. This paper aims to explore how residents respond to noise and vibration mainly induced by the building construction. The noise and vibration measurements, as well as a questionnaire survey, were conducted. Through analysis and comparisons, it is shown that the noise impacts were concentrated in the area near the construction site. For the noise and vibration transmission within the building, the noise levels were amplified in the lower floors and gradually attenuated with floors, and the vibration levels decayed with the floors. The noise impact was much greater than the vibration impact. Building construction was found to be one of the most annoying noise and vibration sources, while the subway operation has little impact on residents according to either subjective or objective evaluation. The ratio of noise and vibration dissatisfaction was less than that of annoyance, which demonstrated that the residents’ psychological capacity was high toward the impact of noise and vibration. The proposed dose-response relationship can apply in a similar community environment. Once the noise levels within the building obtained, the residents’ noise annoyance can then be estimated.

Environmental and Health Effects of Ventilation in Subway Stations: A Literature Review

Environmental health in subway stations, a typical type of urban underground space, is becoming increasingly important. Ventilation is the principal measure for optimizing the complex physical environment in a subway station. This paper narratively reviews the environmental and health effects of subway ventilation and discusses the relevant engineering, environmental, and medical aspects in combination. Ventilation exerts a notable dual effect on environmental health in a subway station. On the one hand, ventilation controls temperature, humidity, and indoor air quality to ensure human comfort and health. On the other hand, ventilation also carries the potential risks of spreading air pollutants or fire smoke through the complex wind environment as well as produces continuous noise. Assessment and management of health risks associated with subway ventilation is essential to attain a healthy subway environment. This, however, requires exposure, threshold data, and thereby necessitates more research into long-term effects, and toxicity as well as epidemiological studies. Additionally, more research is needed to further examine the design and maintenance of ventilation systems. An understanding of the pathogenic mechanisms and aerodynamic characteristics of various pollutants can help formulate ventilation strategies to reduce pollutant concentrations. Moreover, current comprehensive underground space development affords a possibility for creating flexible spaces that optimize ventilation efficiency, acoustic comfort, and space perception.

Noise acceptance of acoustic sequences for indoor soundscape in transport hubs

Noise acceptance is an aspect of indoor soundscape research. While staying or walking in a transport hub, sequential sounds form sequence sounds sessions, which are referred to as an acoustic sequence. The basic phenomenon and effects of acoustic sequences on acceptance evaluations have been explored. A total of 209 sections of 30 s acoustic units were extracted before performing acceptance evaluations. The acoustic units were divided into strong, medium, and weak levels, and compiled into 37 pieces of acoustic sequences, which were then subjected to four tests for acceptance evaluation: sound content, acceptance level, and effects of weak and strong acceptance units. One piece of an acoustic sequence consists of 20 acoustic units. The results show that all acoustic sequences exhibit "attenuation effects"-as for any acoustic unit that makes up the sequence, general acceptance decreases with time. The lower the acceptance, the faster the decay in score. High acceptance units have an "enhancement effect," and the acceptance increases after a high acceptance unit. Low acceptance units have a "boost effect," and the acceptance increases after a low-level acceptance. Both enhancement and boost effects could improve the acceptance evaluation of acoustic sequences and sound experiences in transport hubs.

Effects of combined traffic noise on the synaptic ultrastructure and expressions of p-CaMKII and NMDAR1 in the hippocampus of young SD rats

In order to explore the effects of combined traffic noise (CTN) on learning and memory function, young Sprague-Dawley (SD) rats were exposed to CTN from highway and high-speed railway for 52 days, whose day-night equivalent continuous A-weighted sound pressure level (L_dn) was 70 dB(A) (corresponding sound pressure level was 80 dB). The synaptic ultrastructure and the expressions of phosphorylated calcium/calmodulin-dependent protein kinase II (p-CaMKII) and N-methyl-D-aspartate receptor 1 (NMDAR1 or NR1) in the hippocampus were tested by transmission electron microscopy (TEM) and Western blot, respectively. Results showed that there was no significant difference in the synaptic ultrastructure and the expressions of p-CaMKII and NR1 in the hippocampus of young rats between the experimental group and control group. Compared with single high-speed railway noise (HSRN) with L_dn of 70 dB(A), CTN had less influences on learning and memory function, which was closely related to smaller intermittency of CTN and less anxiety caused by CTN. In comparison with white noise with a sound pressure level of 80 dB, CTN had less impacts on learning and memory function, which was mainly associated with CTN's smaller R-weighted sound pressure level based on rats' auditory sensitivity.

Traffic noise exposure of high-rise residential buildings in urban area

Noise pollution is a major factor of environmental complaints in many cities, which has significant impacts on human health. As a dominating source of environmental noise, the impact of road traffic noise is increasing. Residents living in high-rise buildings along the main road are severely affected by traffic noise. In order to assess the noise level of urban area along the main road in Guangzhou, three buildings were selected to conduct traffic noise measurements, and the questionnaire about traffic noise impact on human being was completed. Through the questionnaire, around 70% of participants consider the traffic noise has negative effect, and about 60% of participants consider the noise has moderate or much higher impact on physical comfort. Around 65% of participants consider the noise had moderately or much higher impact on their psychological comfort. By analyzing the measured data, all of the measured noise levels in three buildings exceed the recommended limit of 55 dB (A) in the daytime and 45 dB (A) in the night for residence, and the exceeded value can be up to 16 dB (A). By comparing the fitting curve of noise level transfer function on each floor relative to the reference floor, the quadratic polynomial was selected to plot the transfer function rather than cubic polynomial.

Assessment of ventilation noise impact from metro depot with over-track platform structure on workers and nearby inhabitants

In order to alleviate the shortage of land use accompanied with urbanization, over-track building complexes above metro depots are developed rapidly in China, resulting in the larger mechanical ventilation needs in the metro depot. Excessive noise exposure caused by the huge ventilation system will bring serious impacts on the health of workers in the metro depot. This research intends to evaluate the noise annoyance in the metro depot and the noise influences on adjacent residential buildings by the ventilation system. A questionnaire survey of 100 people working in a metro depot of Guangzhou Metro Line 6 was conducted, and field measurements inside the metro depot and inside adjacent residential buildings were carried out. The environmental noise level in the metro depot and the ventilation fan-induced noise level inside adjacent residential buildings exceed the corresponding criterion limit of China. Dose-response relationship modeled by logistic function was used to assess the noise annoyance, which is found underestimating the percentage of "Annoyed" (% A) and percentage of "Little Annoyed" (% LA) of staffs in the metro depot, especially for the % LA. This may be attributed to the reducing reliability of dose-effect curves as the L_dn is higher than 65 dB(A). In order to alleviate the noise impact, noise-controlling measures need to be took. However, traditional noise-controlling measures cannot solve low-frequency noise disturbance.

Economic valuation of noise pollution control policy: does the type of noise matter?

As the average noise level and number of noise sources have increased, governments have taken various measures to make soundscapes sustainable. Wise policy decisions require information about the monetary value of noise-control policies. This study elicited people's willingness to pay (WTP) for noise policies, separating traffic noise from residential noise to compare the value of controlling different types of noise. The contingent valuation method was used for the empirical analysis, with data from South Korea. The results show that the monthly mean WTP of respondents was KRW 3392.3 for residential noise reduction and KRW 3507.1 for transport noise reduction; thus, the WTP for the latter is slightly higher than that for the former. Moreover, about 80% of people are unwilling to pay for a noise policy at all, and that high ratio of people with zero WTP must be taken into consideration in the process of policy formulation and implementation. Respondents' experiential and psychological factors were found to be more important than their demographics in explaining their WTP for a noise policy. Potential policy implications based on the analysis results are provided.