A hearing aid with a microphone system (1) and a subsequent analog/digital converter (5). The microphone system (1) is encapsulated in a shielding case (3) and the analog/digital converter (5) is mounted on the shielding case (3). The analog/digital converter (5) is encapsulated in a converter shielding case (7a, 7b) which is set to the potential of the microphone system shielding case (3). The microphone system (1) and the analog/digital converter (5) are releasably attached to one another in a modular manner.