Influences of combined traffic noise on anxiety in mice

With the rapid development of traffic facilities in China, traffic noise pollution is increasingly prominent. This research aims to explore the influences of combined traffic noise on receptors' anxiety. Institute of cancer research mice were exposed to combined traffic noise (CTN) from highway and high-speed railway for 52 days, whose day-night equivalent continuous A-weighted sound pressure level (Ldn) was 70 dB(A). The impacts of CTN on anxiety were explored by behavior tests and monoamine neurotransmitter assays. The results were in depth discussed in comparison to two previous studies on the impacts of single high-speed railway noise (HSRN) and aircraft noise (AN), but data from the three studies were not merged and statistically compared. No significant differences were shown in the behavioral indicators and the monoamine levels between the experimental and control groups after CTN exposure, indicating no obvious impacts of 70 dB(A) CTN on anxiety in mice were found in this study. When Ldn was approximately 70 dB(A), CTN had less obvious impacts on anxiety than HSRN and AN, which is mainly related to that both the acoustical parameters of noise events [maximum noise level (LAmax), noise events duration, slope of rise, difference of LAmax from 1-min background equivalent continuous A-weighted sound pressure level] and modified day-night equivalent continuous R-weighted sound pressure level (considering animal auditory sensitivity to different sound frequencies and circadian rhythms) of CTN are smaller than those of HSRN and AN.