This communication describes a method for both on/off and flow rate control of dry powders in open capillaries using acoustic vibration. In a glass capillary attached to an electromagnetic transducer, the wave characteristics of the forced vibration control both flow rate and switching of powder flow. The valve is free from relative movement of parts that may wear or seize in the presence of fine powders. The versatility of the flow controller has been demonstrated by playing popular music to a sample of H13 tool steel powder. The on/off switching and the flow rate of the powder correspond to the waveform of the music. (C) 2003 Elsevier B.V. All rights reserved.