The invention provides a display apparatus having a temperature sensor and a step-up circuit generating a drive voltage of the display apparatus by stepping up a power source voltage. The composite board’s mesh layer incorporates a stretchable mesh which in conjunction with the polystyrene substrate and the non-shrinking cement compound supports standard fasteners used in the home-building industry along with providing a suitable tile adhesion surface. Filter adaptation is controlled by a controller based on the rate of the far-end speech signal, the rate of the near-end signal, an acoustic loss measure, and a double talk hangover indicator. The sliding surface includes the surface texture, in which the hard part and the tough part that supports the hard part are present in a mixed fashion with a micro-meso region level, and stably exhibits excellent wear resistance.