Confused by all the different kids of microphones available to you? If so, this little intro to mics might be just what you need to clear up some of the confusion.
Ok, our topic is Microphones. I'll discuss some common types of mics and how they work. First off, a microphone is a transducer, which is a device that transforms energy into another corresponding form of energy. Other transducers you may be familiar with are speakers, headphones, and yes… your ears. In this case, the 'energy' being converted by the mic is sound pressure level, or SPL, which is received by the diaphragm of a mic then transformed into a corresponding small AC voltage (mic level).
The most common microphones used in recording today fall in these categories:
Now that you've learned about the different types, you must learn the different polar response patterns of a mic's capsule. The response pattern tells you how or from what direction a mic will pick up sound.
These are the different types:
This pattern receives SPL from all around it. In Fig. 1 you see the response pattern of an omni mic. Its capsule is located at the origin of the x and y axis pointed towards the 0 degree mark. As you can see the circle represents that it will receive SPL equally from all angles.
These patterns are more directional, meaning that they have specific points of SPL rejection.
Unidirectional - Picks up sound primarily from one direction.
Bidirectional (commonly known as figure 8)
As seen in fig.3, it will receive SPL from in front and back of the capsule but reject sounds coming from the sides. This characteristic is very valuable for stereo imaging as we'll discuss in Part 2 of this article.
Most Dynamic mics have a fixed polar pattern. Condenser microphones can have the ability to switch patterns and those that do will have 2 capsules to help achieve the different responses by manipulating the 2 signals.
*Stay tuned for The Mic Demystified: Part 2 for some common applications of these different mic types, to see how these polar response patterns can be used in recording, and some tips on stereo imaging.
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