MICROPHONE DIRECTIVITY & POLAR PATTERNS
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Which microphone polar pattern fits my project's sound?
Microphone directivity, also known as polar pattern, describes how well a microphone picks up sound from different directions. It's basically its ability to focus on specific sounds based on where they're coming from. This characteristic is visualized in a graph called a polar pattern. Understanding this concept is crucial for selecting the right microphone for specific applications. |
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Major Directivity Types |
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Imagine the microphone at the center of a circle. The polar pattern will show a line around the circle, with the distance from the center indicating how sensitive the microphone is to sounds arriving from that direction. Here are the main types of polar patterns based on directivity:
Check the polar patterns in 3D !
(*These 3D images illustrate equal sound pressure surfaces based on those polar patterns, and the polar patterns do not directly indicate the area of sound pickup coverage.)
(*These 3D images illustrate equal sound pressure surfaces based on those polar patterns, and the polar patterns do not directly indicate the area of sound pickup coverage.)
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*The directivity of all microphones is frequency dependent, so it is highly recommended to check polar patterns if you like to know frequency-specific sensitivity performances.
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How it is measured? |
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Microphone frequency response and polar patterns are two interrelated measurements used to characterize a microphone's performance. The frequency response refers to how sensitive a microphone is to different sound frequencies. It's typically measured in an anechoic chamber (an almost completely soundproof room) using a calibrated sound source like a loudspeaker. The source emits pure tones (sine waves) at various frequencies, and the microphone's output is measured at each frequency. The resulting data is plotted as a graph showing the microphone's sensitivity across the frequency spectrum.
In order to create a polar pattern, sound sources are positioned around the microphone at specific increments (usually every 15 or 30 degrees) and the frequency response is measured at each position.
In order to create a polar pattern, sound sources are positioned around the microphone at specific increments (usually every 15 or 30 degrees) and the frequency response is measured at each position.
Anechoic Chamber at TOA Corporation in Japan
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Exploring the Individual Characteristics |
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Let's explore the different polar patterns associated with microphones.
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Omnidirectional
These micophones are like little sound sponges, picking up sound equally from all directions (think of a sphere). This makes them good for capturing the whole atmosphere of a space or recording multiple people speaking at once. Suitable applications: Studio recording, room microphones, capturing wide sound sources (such as choirs). |
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Unidirectional - Cardioid
These microphones are most sensitive to sounds coming directly in front of them. They have less sensitivity on the sides and back, making them ideal for isolating a specific vocalist or instrument in a noisy environment. Suitable applications: Live performances, speeches/presentations, paging announcements, and situations where ambient noise needs reduction. |
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Unidirectional - Super-cardioid
These microphones are are similar to cardioid but have narrower sensitivity angles. They are more directional and have increased rejection of sounds from the sides while also having some rear pickup. Suitable applications: Broadcast, field recording, speeches/presentations, paging announcements, and live sound reinforcement. |
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Unidirectional - Hyper-cardioid
These microphones have even narrower sensitivity but are significantly more sensitive to sound from behind than super-cardioids. The rear sensitivity can be problematic if there's unwanted noise coming from behind the mic. Suitable applications: Broadcast, field recording, speeches/presentations, paging announcements, and live sound reinforcement. |
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Bidirectional (Figure-of-Eight)
These microphones have a null zone on the sides, resembling the number eight. They pick up sound equally from the front and back, making them useful for recording interviews or duets where two people are facing each other. Suitable applications: Interviews with two people or duets where two people are facing each other. |
Ready to Dive Deeper into Microphone Sensitivity?
In order to select the right microphone, it is also important to understand the factor "microphone sensitivity".
Check out this article for a more in-depth exploration of this important audio concept!
Check out this article for a more in-depth exploration of this important audio concept!
