Abstract: A compressor including a chamber having a standing acoustical wave therein, the wave having at least first and second velocity nodes, the first velocity node having a smaller cross-sectional area than the second velocity node, a high pressure inlet adapted to receive relatively high pressure gas, an inlet mechanism operably connected to the high pressure inlet and to the chamber, the inlet mechanism being associated with the first velocity node and adapted to supply pulses of the relatively high pressure gas to the chamber at a predetermined rate, at least one outlet valve associated with the second velocity node of the chamber and adapted to allow gas at a relatively low pressure to pass therethrough, and a low pressure inlet operably connected to the chamber.