An acoustic module, such as a microphone or speaker module, includes an acoustic membrane that vibrates to produce acoustic waves and an acoustic cavity through which acoustic waves produced by the membrane travel. A liquid removal mechanism removes liquid from the acoustic cavity. Such a liquid removal mechanism may include the acoustic membrane, heating elements, hydrophobic and/or hydrophilic surfaces, and so on. In some cases, the liquid removal mechanism may remove liquid from the acoustic cavity upon connection of the acoustic module and/or an associated electronic device to an external power source.