Array technique well known in seismology is applied to acustical signals in the subsonic or infrasonic frequencyband.
This is achieved by simply changing the detector, and scaling the dimensions of the array according to the differences between acoustic and seismic velocities.
The design of a robust detector is taken from Hugo Benioff.
The atmosphere is more homogeneous than the solid earth on length scales of the array but varies strongly with time due to wind and temperature variations.
This leads us to reevaluate the array design.
Recent techniques to process the data, borrowed from seismology, are described.
Finally various trade-off in array processing are mentioned in order to make clear that different objectives could guide between various array processing techniques.
Some results are discussed from measurements with a six-element array mainly focussed at sonic boom detections.
HW Haak. An acoustical array for subsonic signals