A power control circuit is driven by electric power supplied from a controller as an external device via a cable, and controls openingclosure of a switch in accordance with instructions from the controller. The aforementioned environmental parameters include at least the following: measurement and control of temperature, agitation and aeration, measurement and control of pH and dissolved oxygen and measurement of the biomass. Thus, there can be provided a wafer heating apparatus having an electrostatic adsorption function that has sufficient electrostatic adsorption power without causing dielectric breakdown when electrostatically adsorbing and heating wafers. A hub carrying impellers is rotatably mounted on the weldment post. Each of the headphones further comprises a driver mounted within the driver mount and including a diaphragm, a foraminous unitary diaphragm support for maintaining the driver within the driver mount, an earcup cover attached to the earcup, and an earpad attached to the earcup. An air-inlet valve is mounted on the pump member for closing the opening in the cover cap, and is operable to uncover the opening in the cover cap.