A remote microphone device for a hearing aid system comprises a multitude of microphones providing a corresponding multitude of electric input signals; a digital signal processor for providing a processed signal in dependence of said multitude of electric input signals. The processor comprises a noise reduction system comprising at least one beamformer for providing a spatially filtered signal. The remote microphone device further comprises a wireless communication interface comprising antenna and transceiver circuitry allowing the remote microphone device to transmit said processed signal comprising said spatially filtered signal or a further processed version thereof to said hearing aid system; a rechargeable battery; a casing having a planar structure with a form and size as a standard credit card; and a user interface configured to allow the user to control functionality of the remote microphone device. The invention may e.g. be used in hearing aid systems or headsets.