The effectiveness of acoustic signals on the evacuation in underground space

The development of urbanization in China has provided external pressure and intrinsic conditions for the exploitation and utilization of underground space in many Chinese cities. Due to the closed environment, smoke and heat is difficult to exclude naturally when a fire occur at the underground space. The emergency evacuation signs could be easily blocked by the smoke, whereas the acoustic signals are not affected. This study aims to explore the effectiveness of acoustic signals on the evacuation at the underground space, by means of simulated fire experiment. The underground air-raid shelter in Chongqing University was selected as the experiment site, full of real smoke. A total of 60 university students took part in this experiment voluntarily, and they were randomly divided into 3 groups (10 males, 10 females for each group). Group A had no acoustic signals in the scene of smoke as the control group, while Group B and Group C were provided with alarm sound and voice sound respectively, as the acoustic evacuation guide. All the participants were given the information sheet before they signed the consent form. To ensure the health and safety of participants, each of them was asked to wear a self-priming filter mask during the experiment. As expected, there are significant differences between the audio signal-guided group and control group in terms of evacuation time, given 33.34% and 36.05% less time spent in Group B and Group C. With regard to the gender effect, although male's evacuation speed is generally faster, in the absence of acoustic signal guidance, the male are more likely to fail the evacuation than female. However, with the guidance of sound signal, the evacuation efficiency of male subjects tends to be better than female. In addition, acoustic signals can greatly improve the choice of the right path for evacuation personnel.