Investigation of combined effects of noise and low air temperature on human-environmental comfort and physiological responses- An experimental study

Background and Aim: Combined exposure to noise and temperature can affect the neurophysiological responses of the office staff. The present study was done to investigate the impacts of combined exposure to noise and low air temperature on physiological responses and environmental comfort. Methods: In this experimental study, the studied population included the students who were randomly selected from Hamadan University of Medical Sciences in June 2018. This study was conducted on 24 students who were exposed to ten different conditions set by a combination of low air temperatures of 14, 18, and 22  and noise levels of 55, 65 and 75 dB in a climate chamber. The duration of each session was 55 minutes. Physiological parameters such as blood pressure, heart rate, body temperature, finger skin temperature, galvanic skin response, and respiration rate were measured before and after exposure. Thermal sensation and thermal comfort votes were measured using ISO 10551 standard. Sensitivity to noise was also measured using ISO15666 standard scales for noise annoyance. Results: Within the range of the studied temperature and noise, the effect size of reducing air temperature on physiological responses was higher than the effect size of increasing noise (P <0.05). By reducing air temperature, noise annoyance reported worse and also the thermal perceptions were affected by increasing noise at cold air temperature (P <0.05). The mean changes of galvanic skin response, respiration rate, heart rate, and noise annoyance when exposed to irrelevant speech have increased as compared with the fan noise and these changes were statistically significant (P <0.05). Conclusion: The finding of this study showed that the decrease in air temperature compared with the increase of noise led to a more increasing in subjects' physiological responses. Moreover, temperature affected the score of noise annoyance and thermal perceptions were influenced by noise. Also, exposure to irrelevant speech in offices is very effective for employees' comfort.