Flexible differential microphone arrays with fractional order

A method for constructing a fractional order beamformer, for a differential microphone array (DMA) including a number M of microphones, the method comprising:

• specifying, by a processing device, a target white noise gain (WNG) value for the DMA;
• generating, by the processing device, an N+1 order beampattern and N+1 order beamformer for the DMA, wherein N is an integer value and a first WNG value corresponding to the N+1 order beamformer is smaller than the target WNG value;
• generating, by the processing device, an N order beampattern and N order beamformer for the DMA, wherein a second WNG value corresponding to the N order beamformer is greater than the target WNG value;
• and
• generating, by the processing device, a fractional order beampattern and the fractional order beamformer for the DMA, wherein a third WNG value corresponding to the fractional order beamformer matches the target WNG value and the fractional order beampattern comprises a first fractional contribution from the N+1 order beampattern and a second fractional contribution from the N order beampattern.

A system comprising:

• a data store;
• and
• a processing device, communicatively coupled to the data store and to a number M of microphones of a differential microphone array (DMA), to:
• specify a target directivity factor (DF) value for the DMA;
• generate an N order beampattern for the DMA, wherein N is an integer and a first DF value corresponding to the N order beampattern is greater than the target DF value;
• generate an N−1 order beampattern for the DMA, wherein a second DF value corresponding to the N−1 order beampattern is smaller than the target DF value;
• and
• generate a fractional order beampattern for the DMA, wherein a third DF value corresponding to the fractional order beampattern matches the target DF value and the fractional order beampattern comprises a first fractional contribution from the N order beampattern and a second fractional contribution from the N−1 order beampattern.

A differential microphone array (DMA) comprising:

• a number M of microphones located on a substantially planar platform;
• a processing device, communicatively coupled to the M microphones, to:
• specify a target directivity factor (DF) value for the DMA;
• generate an N order beampattern for the DMA, wherein N is an integer and a first DF value corresponding to the N order beampattern is greater than the target DF value;
• generate an N−1 order beampattern for the DMA, wherein a second DF value corresponding to the N−1 order beampattern is smaller than the target DF value;
• and
• generate a fractional order beampattern for the DMA, wherein a third DF value corresponding to the fractional order beampattern matches the target DF value and the fractional order beampattern comprises a first fractional contribution from the N order beampattern and a second fractional contribution from the N−1 order beampattern.

A non-transitory machine-readable storage medium storing instructions which, when executed, cause a processing device to:

• specify a target directivity factor (DF) value for a differential microphone array (DMA) with a number M of microphones;
• generate an N order beampattern for the DMA, wherein N is an integer and a first DF value corresponding to the N order beampattern is greater than the target DF value;
• generate an N−1 order beampattern for the DMA, wherein a second DF value corresponding to the N−1 order beampattern is smaller than the target DF value;
• and
• generate a fractional order beampattern for the DMA, wherein a third DF value corresponding to the fractional order beampattern matches the target DF value and the fractional order beampattern comprises a first fractional contribution from the N order beampattern and a second fractional contribution from the N−1 order beampattern.