Two series of experiments were conducted to investigate time response of the human physiological reactions and heat balance between the humans and their environment during exposure to the combinations of temperature and noise conditions. Ten Japanese male students were exposed to twenty-five combined conditions of operative temperature (27, 30, 33, 36, 39 degC) and noise (46.8, 59.2, 73.1, 80.0, 95.4L_Aeq) in summer and eight of them were also exposed to twenty combined conditions of operative temperature (19, 22, 25, 28 degC) and noise (46.6, 58.5, 72.9, 79.9, 95.5L_Aeq) in winter. The skin and oral temperatures, metabolic rate, sensible heat transfer rate were continuously measured.

The following results were obtained: noise was not found to affect measured physiological responses. Mean skin temperature fell gradually for 19, 22 and 25 degC conditions, and was stable for another hotter conditions. Oral temperature was 36-37 degC stably. Sensible heat rate fell down gradually for 19 and 22 degC conditions. that is the evidence that there is no discrepancy between mean skin temperature and sensible heat rate. There were no seasonal difference of latent and sensible heat transfer rates. However, metabolic rate for all conditions was stable at 40-45 W/m2 in winter and at 45-50 W/m² in summer, respectively. Thus, metabolic rate in winter were lower in about 5-10 W/m² than that in summer. This finding supports recent studies for Japanese subjects, but not the previous studies conducted several decades before for Canadian and Japanese. It may be due to a change of diet between generations and nations.