According to an embodiment, a microspeaker includes an acoustic micropump structure configured to pump at a first frequency above an upper audible frequency limit. The acoustic micropump structure is further configured to generate an acoustic signal having a second frequency by adjusting the pumping. Adjusting the pumping includes adjusting a direction of pumping for the acoustic micropump structure according to the second frequency. Adjusting the direction of pumping includes changing a direction of flow of an elastic medium through the acoustic micropump structure from a first direction to a second direction. The second frequency is below the upper audible frequency limit.