R&D Report 1954-23 : The Neumann microphone Type U47 H.D. Harwood, R.J. Packer A new directional electrostatic microphone, type U 47, produced by the firm of Neumann in Berlin, incorporates the capsule originally designed for the type M 49 microphone but uses a cheaper form of head amplifier. The U 47 microphone is designed to give either cardioid or omnidirectional polar response. Frequency characteristics, sensitivity and noise have been measured on a single specimen for both conditions. The response of the microphone capsule in the cardioid condition is very good, but the overall performance is spoilt by the obstacle effect of the large head amplifier. The signal-to-noise ratio is unusually high. In the omnidirectional condition the microphone is of no special interest.