ABSTRACT
This varying sensitivity versus angle can be graphed as a polar pattern or polar response (see Figure 7-1). Polar patterns are plotted on polar graph paper as follows: In an anechoic chamber, the microphone is exposed to a tone of a single frequency and its output voltage is measured as it is rotated around its diaphragm. The voltage at 0º (on-axis) is called the 0 dB reference, and the voltages at other angles are referenced to that. In other words, the polar-response graph plots relative sensitivity in dB versus angle of sound incidence in degrees. Often, several such plots are made at various frequencies. Note that the microphone rotation should be clockwise if the degree marks increase in a counterclockwise direction.
