What are Polar Patterns?
The Polar Pattern of a microphone refers to the sensitivity of a microphone to sound arriving from different angles to its central axis. This pattern is what determines the direction(angle) at which we point the microphone to the source of the sound that we want to record.
How do Microphones work?
The microphone is a type “transducer”; a device that converts one form of energy to another in this case, sound energy into electrical energy. The different kinds of microphones vary vastly on the function of converting the energy but, one part, by function, is always the same; The Diaphragm. This is the part of the microphone that picks-up the sound. When the diaphragm vibrates, it causes other components in the microphone to vibrate. These vibrations are converted into an electrical current which becomes the audio signal.
How to understand the Polar Pattern Chart?
Looking at the Polar Pattern diagrams, the smallest concentric circle stands for the head of the microphone. This is the part of the microphone that picks up the sound. The bold circular shapes surrounding the microphone is how sensitive to the microphone is to the sound coming from that direction.
Looking at the Omnidirectional Microphone’s Polar Pattern, we see that the microphone is sensitive to sound coming from all directions. And the Subcardioid microphone has a slight rejection(isn’t as sensitive) towards the rear of the mic, and likewise, the Cardioid has almost total rejection towards the rear of the mic. The Specifications chart of the microphone will have superimposing patterns that show the sensitivities of multiple frequencies because each frequency reacts differently due to its physical nature. Remember that though this chart is two-dimensional, this affects the microphone in three-dimensional space.
This microphone picks up sound equally from all directions. This means that the direction the microphone is pointing is not important but proximity to the source is what matters in capturing the sound.
This microphone is best used to capture multiple sound sources at the same time like capturing a choir around a single microphone. This is also the best microphone to record ambiance.
This microphone captures sound in front of it. This also helps in rejecting the noise at the back of the microphone. This helps in reducing ambient noise and giving a clear capture of the source it’s pointed towards.
This microphone is used to record one source, or a close group of sources like a lead singer on-axis and 2 backup singers off-axis to emphasize the lead artist and also have the backing vocals lift the lead singer through one microphone.
Supercardioid and Hypercardioid Microphones:
These microphones have a narrower field of capture in the front of the microphone, but they have a sensitivity to the sound coming from the rear of the mic. So while these microphones have a narrower field of capture, their position greatly affects the sounds being picked up from the rear of the mic.
These mics are used to pick up sound from a source that requires isolation from other sources.
If you wanted to record a choir and record each male and female part separately to blend later on while mixing, these types of microphones will help you capture these sources simultaneously with a good degree of isolation so you can affect each part separately.
The figure of 8/Bi-Directional Microphones:
This microphone picks up sound from the front and the rear of the microphone with equal sensitivity and rejection from the sides of the microphone resulting in a figure of 8 like pattern.
This microphone is best used to record two sources at the same time, like a conversation or a podcast with two people seated opposite each other.
This Microphone is the most directional. These microphones are used to capture a sound from a source at a significant distance away from it.
These microphones are used during film making to record actor dialogue.
Using this knowledge:
Now knowing how to read a Polar Pattern chart, what it all means, this should allow you to use microphones with much better accuracy. Understanding how a microphone captures and rejects sound should enable you to capture the sound you want even though there are sounds you don’t want to capture in the surrounding environment.