Analysis of distortion in audio signals introduced by microphone motion

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 motion-induced distortion, and showing that the dependence of this upper bound on motion speed, signal frequency, and time-frame duration, is linear. A simulation study of a humanoid robot rotating its head while recording a speech signal validates the theoretical results.