This paper presents the phenomenon in which circularly rotating sound sources exhibit a spectral split at the center of rotation. It is shown that this spectral split occurs exclusively in the velocity field and is equivalent to the angular speed of the rotation. However, it does not affect the pressure field at the point of measurement, showing no change to the emitted spectrum of the source. To test this in both 2D and 3D, the sound field of a rapidly rotating sound source is reconstructed using Wavefield Synthesis. The reconstruction is done as faithfully as possible by minimising the discretisation artifacts using a large number of secondary sources along the circle perimeter and sphere surface respectively. The measurements taken confirm the theoretical findings. The applications of this phenomenon can range from fault analysis of rotating machines to spatial audio and may also inform on the perception of rotating sound beyond the previously determined limit.
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https://aes2.org/publications/elibrary-page/?id=22126
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