Beamforming method based on arrays of microphones and corresponding apparatus

A beamforming apparatus, comprising:

• a plurality of microphones arranged in an array or in arrays, each microphone configured to generate a microphone signal;
• a processing module configured to receive the microphone signals from said plurality of microphones and to combine said microphone signals to obtain Virtual Microphones (V1 . . . VN), wherein said module is further configured to:
• combine said microphone signals to obtain at least a pair of directional Virtual Microphones having respective patterns of radiation with a same origin corresponding to a reference point of the array and rotated at different pattern direction angles defining a separation angle between them so that at least a circular sector is defined between said different pattern direction angles, said separation angle between the at least a pair of Virtual Microphones being less than π/2;
• and
• obtain a sum radiation signal of a sum Virtual Microphone, to which is associated a respective sum radiation pattern, associate a respective weight to the signals of said pair of directional Virtual Microphones, obtain respective weighted signals of radiation and sum said weighted signals, compute said respective weights as a function of a determined pattern direction angle of the pattern of radiation of said pair of directional Virtual Microphones and of the separation angle so that a main lobe of said sum radiation pattern is steered within said circular sector to point in the direction of said determined pattern direction angle.

A non-transitory computer program product that can be loaded into the memory of at least one computer and comprises portions of software code suitable for, when the program is run on the at least one computer, executing the method comprising:

• receiving microphone signals from a microphone array including a plurality of microphones;
• combining the microphone signals to form a pair of directional virtual microphones having respective signals determining respective patterns of radiation with a same origin corresponding to a reference point of the microphone array and rotated at different pattern direction angles;
• defining a separation angle between the patterns so that at least a circular sector is defined between the different pattern direction angles, the separation angle between the at least a pair of directional virtual microphones being less than approximately π/2;
• determining a sum radiation signal of a sum virtual microphone having an associated sum radiation pattern;
• associating a respective weight to the signals of the pair of directional virtual microphones;
• determining respective weighted signals of radiation and summing the weighted signals;
• computing the respective weights as a function of a determined pattern direction angle of the pattern of radiation of the pair of directional virtual microphones and of the separation angle so that a main lobe of the sum radiation pattern is steered within the circular sector to point in the direction of the determined pattern direction angle.