A method and apparatus for a modular hearing aid for a user having a hearing canal, including a housing adapted to fit within at least a portion of the hearing canal, and having at least one access port, a cover adapted for at least partially covering the at least one access port, and signal processing electronics connected to a microphone and a power supply. In various examples, a microphone housing is adapted to mount to the housing and to fit within the at least one access port, and to connect to the microphone, the signal processing electronics and the power supply. In one variant, the apparatus includes a receiver connected to the signal processing electronics, and a fastener as a unitary connector of the cover and microphone housing to the housing. Other variations are presented herein.