The electret capacitive microphone element is ideally suited for miniature applications. However, because these miniature elements represent very high impedances at audio frequencies, a complete microphone will almost always incorporate a high input impedance preamplifier, which is a source of noise in the microphone. Proper design of both the preamplifier and electret element is required in order to avoid poor signal‐to‐noise ratio. The electret element and accompanying preamplifier are electrically modeled to indicate the important parameters for minimizing the noise. This model is then coupled with the performance equations for two simple electret element geometries to indicate the effects of a noisy preamplifier on the optimum element design. The results indicate that the best signal‐to‐noise level is not obtained at the design point which yields the maximum acoustic sensitivity, but at conditions which maximize the electret element capacitance. The characteristics of two typical wide‐band electret microphones are given to indicate the type of performance actually possible from very small microphones.