Embodiments of the invention provide microphone assemblies for hearing aids which are resistant to moisture and debris. An embodiment provides a microphone assembly for a CIC hearing aid comprising a microphone housing including a housing surface having a microphone port, a fluidic barrier structure coupled to the housing surface, a protective mesh coupled to the barrier structure and a microphone disposed within the housing. The microphone housing can be sized to be positioned in close proximity to another component surface such as a hearing battery assembly surface. At least a portion of the housing surface and/or the barrier structure are hydrophobic. The barrier structure surrounds the microphone port and is configured to channel liquid and debris away from entry into the microphone port including matter constrained between the housing surface and another surface.