Abstract: Method and apparatus for infrasonically intensifying a glow bed (13), supported by a grate (12). In order to improve the beneficial effect of sound on combustion the bed of fuel, located on the grate, is exposed to a high particle velocity of a sound positively produced by an external low frequency sound generator (11) the frequency of which is determined by the sound generator, to provide a reciprocating movement of combustion air and combustion gas through the glow bed. The dimensions of the grate in a plane transverse to the reciprocating movement of combustion air and combustion gas are less than a quarter of the wave-length of the sound generated by the sound generator.