Digital Sound & Music: Concepts, Applications, & Science, Chapter 1, last updated 6/25/2013
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Figure 1.12 Polar plot for an omnidirectional microphone
A bidirectional microphone is often referred to as a figure-eight microphone. It picks up sound
with equal sensitivity at its front and back, but not at the sides. You can see this in Figure 1.13,
where the sound level decreases as you move around the microphone away from the front (0) or
rear (180), and at either side (90 and 270) the sound picked up by the microphone is
essentially none.
Figure 1.13 Polar plot for a bidirectional microphone
Directional microphones can have a cardioid (Figure 1.14) a supercardioid (Figure
1.15), or a hypercardioid (Figure 1.16) pattern. You can see why they‟re called directional, as
the cardioid microphone picks up sound in front but not behind the microphone. The super and
hypercardiod microphones behave similarly, offering a tighter frontal response with extra sound
rejection at the sides (the lobe of extra sound pickup at the rear of these patterns is simply an
unintended side-effect of their focused design, but usually isn‟t a big issue in practical
situations).
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