V2MA (VSVerb Virtual Microphone Array)Demos and related docs are available at https://bit.ly/3BmDBbL .Once we have measured a set of four impulse responses (IRs) with an A-format microphone in a hall, we can make a virtual recording using a virtual microphone array built in the hall at will. The measurement does not require an A-format microphone and a loudspeaker to be placed at specific positions in the hall. Typical positions, such as at an audience seat and on a stage, are recommended, but you can place them anywhere you like. We will generate any type of virtual microphone response in a target room from an easy one-time IR measurement.
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We propose a method, V2MA, that virtually generates acoustic responses of any type of microphone array from a single set of FOA responses measured in a target room. An A-format microphone is used for the measurement, but no Ambisonics operation is included in the processing. V2MA is a method based on geometrical acoustics. We calculate sound intensities in the x, y, and z directions from a measured FOA response, then the virtual sound sources of the room are detected from them. Although it is desirable to have an A-format microphone place close to the attempted position of the virtual microphone array in the room, it is not a mandatory requirement. Since our method allows to generate SRIRs at arbitrary receiver positions in the room by updating the acoustic properties of the virtual sound sources detected at a certain position of the room, an A-format microphone can be placed anywhere you like. On the other hand, a loudspeaker must be placed at the source position where a player is assumed to be. Since the positions of virtual sound sources change when a real sound source moves, we used to measure the responses for each assumed real source position. To improve this inconvenient restriction, we developed the technique of updating the positions of the virtual sound sources when a real sound source moves from its original position. Although the technique requires some approximations, it is ascertained that the generated SRIRs provide fine acoustic properties in both physical and auditory aspect.
