Line Microphones

A line microphone with useful directivity normal to the line axis is described. Several types of line microphones with useful directivity along the line axis are described as follows: A simple line, a line with progressive delay, two simple lines and a pressure-gradient element, two lines with progressive delay, and a pressure-gradient element. An ultra-directional microphone employing line elements exhibits uniform directional characteristics over the range from 85 to 8000 cycles.