Signals recorded by microphones form the basis for a wide range of audio signal processing systems. In some applications, such as humanoid robots, the microphones may be moving while recording the audio signals. A common practice is to assume that the microphone is stationary within a short time frame. Although this assumption may be reasonable under some conditions, there is currently no theoretical framework that predicts the level of signal distortion due to motion as a function of system parameters. This paper presents such a framework, for linear and circular microphone motion, providing upper bounds on the motioninduced distortion, and showing that the dependence of this upper bound on motion speed, signal frequency, and timeframe duration, is linear. A simulation study of a humanoid robot rotating its head while recording a speech signal validates the theoretical results.