Experimental Study on the Effect of Urban Road Traffic Noise on Heart Rate Variability of Noise-Sensitive People

Epidemiological studies have confirmed that long-term exposure to road traffic noise can cause cardiovascular diseases (CDs), and when noise exposure reaches a certain level, the risk of related CDs significantly increases. Currently, a large number of Chinese residents are exposed to high noise exposure, which could greatly increase the risk of cardiovascular disease. On the other hand, relevant studies have found that people with high noise sensitivity are more susceptible to noise. And it is necessary to pay more attention to the high noise-sensitive people. This study investigated the acute physiological effect of different noise-sensitive groups by indoor-level noise stimulus experiments under laboratory conditions, by observing heart rate variability (HRV) indicators, including standard deviation of NN intervals (SDNN), low frequency/high frequency (LF/HF), and heart rate (HR). The results showed that (a) there was no significant difference in HRV between the high-sensitive group and the low-sensitive group at the physiological baseline and the different stimulating noise levels. (b) Then, based on the theory of cumulative effect of noise proposed by WHO Regional Office for Europe, non-significant but observable differences between groups were further discussed. By analyzing differences of the variation trends and the within-group significant changes of SDNN and HR between the two groups, the results tended to show that the high-sensitive group is more affected by road traffic noise. In addition, the values of SDNN and HR showed observable between-group differences at 55 dB (A) and 65 dB (A) which corresponding to the SPL associated with a significantly increased risk of cardiovascular disease concerned by epidemiological studies. According to the cumulative effect theory (WHO), these differences in HRV caused by short-term noise stimulation may have the potential to produce physiological response and lead to between-groups differences in prevalence after long-term recurrent effect, and deserve attention and further research.

Influence of road traffic noise peaks on reading task performance and disturbance in a laboratory context

The influence of fluctuating road traffic noise on perceived disturbance during a reading task as well as on performance, inside a living room with closed windows, is presented in this paper. Sixteen 2-min sound sequences were created combining two variables: the number of events (four levels varying from one to four car pass-bys) and the peak emergence above the background noise (four levels with a 5 dB(A) step) keeping limited variations of LAmax, 1s. The noise impact was evaluated through a reading task of texts synchronized with the sound sequences, for participants classified into fast or slow readers, and sensitive or non-sensitive to noise. The comprehension rate of the texts decreases as the background sound level increases. The reading speed decreases during the rising front of a peak, and goes back to its former regular reading speed during the descending front of the peak. This slowdown during the rising front reaches 14% for slow readers. The declared disturbance is higher for slow readers compared to fast readers, and higher for noise sensitive persons compared to non-sensitive persons. The influence of the acoustic indicators on the reading disturbance is very small compared to the influence of personal factors. There is even no influence of the number of events on this disturbance.

Road traffic noise assessment in a hospital area in Umuarama - Brazil

In hospital environments, high noise levels can result in damage to patients' treatments, delaying their rest and recovery. The sound pressure level (SPL) in hospital areas during the day must not exceed 50 dB and 45 dB (A) at night, according to NBR 10.151/2019. This research aimed to carry out environmental monitoring of equivalent sound pressure levels (LAeq) at fifteen points in the vicinity of three hospitals in the central region of the municipality of Umuarama-PR, during working days, at four different times, in the months of August, September and November 2018 and continued in March 2019. To this end, we sought to map the LAeq of the points, compare them with data from municipal and federal legislation and relate the LAeq to the volume of vehicular traffic. The collected SPL were higher than recommended by NBR 10.151 at all times and measurement points, during the week, and when considering the municipal regulations, only one point is in the equipment's accuracy limit. From the statistical analysis, a very strong correlation was observed between LAeq and the total volume of vehicles, and also a strong correlation between the descriptors L10 and L50 and the volume of vehicles. The Traffic Noise Index (TNI) was also calculated and the LAeq values ​​were compared with a subjective noise rating. The results show a scenario of noise pollution in the area and there is a need for the application of mitigating measures.