Listening to the direct sound of musical instruments in freely adjustable surrounding directions
Christian Nachbar, Gerold Nistelberger, and Franz Zotter
This contribution demonstrates a piece of software named vMIC (virtual microphone) that processes sound-radiation data from musical instruments. vMIC uses 64 channel recordings taken by a surrounding spherical microphone array. The 64 microphones of this arrangement capture the direct sound of the recorded instrument at 64 discrete directions of radiation hence represent a nearly complete acoustic image of the instrument. Instead of graphical analysis of the directional sound radiation, we consider listening to the recordings directly. For this purpose, vMIC uses a controllable virtual microphone position for which the direct sound of the instrument is computed by hyperinterpolation in real-time. Spherical harmonics hyperinterpolation provides seamless interpolation between the discrete directions of the microphone array, yielding the audio signal of the virtual microphone carrying the matter of our interest: a timbre and loudness depending on the direction. To maintain a geometric overview, vMIC renders a graphical output of the construction of the recording layout including symbols for the instrument, the musician, and the virtual microphone position.