Microphone Pickup Patterns
Whether you are purchasing a brand new microphone or are wanting to get the best performance out of your existing device, it's important to understand how your microphone picks up the sound around it. This is known as the microphone's pickup pattern (or polar pattern).
As shown in the picture, the pickup pattern (the shaded plum shape) represents the area around the microphone that is most sensitive to sound. Any sound source that is outside the shaded area will be prone to sound rejection. Knowing your microphone's pickup pattern will help you better understand your microphone placement options to get the clearest sound with minimal background noise or unwanted feedback (the high pitched screech common in poor microphone/speaker setups). Although there a many different types of pickup patterns, we will outline the 3 most common ones present in consumer electronics.
Cardioid (Unidirectional) Pickup
The Cardioid pickup pattern, which is also commonly known as Unidirectional, is one of the most common pickup patterns in consumer electronics and professional recording equipment. This type of pickup pattern is common on devices such as smartphones, tablets, and laptops where speech clarity is the priority. Handheld microphones (such as those commonly used for karaoke), most webcam microphones, and USB podcast/broadcasting microphones with a cardioid option also use this pickup pattern.
Its name comes from the fact that the polar diagram (360 degree graph on the left) is shaped like an upside down heart. When this diagram is turned into a 3D shape, it looks like a peach or plum (like the diagram shown before).
Anything inside the general shape of the cardioid pickup pattern is where sound recording is most sensitive. The area behind the microphone's capsule (180 degrees on the diagram) is able to reject the most background noise. Because of this directional nature, it is important that you aim the front (or sides to an extent) of the microphone capsule towards you and your instrument.
The Omnidirectional pickup pattern is common in many USB condenser microphones, such as the Blue Snowball and Yeti, and professional audio microphones, such as large-condenser microphones for room recording of instruments. It is also found on certain models of webcams and microphone/speaker combos used for group video conferencing.
Its name comes from the fact that the microphone's capsule picks up sound equally in all directions. In a 3D space, you can imagine this field as a large sphere around the microphone. This makes omnidirectional microphones perfect for situations where you want to capture the sound of an entire room, like a small music studio with nice acoustics or a group business meeting with multiple speakers in one room.
This ability to capture everything is also an omnidirectional microphone's biggest weakness, as they are very susceptible to outside noise. Microphone placement therefore can be either simple or complicated in comparison to cardioid microphone. In a quiet and controlled room, you can realistically place an omnidirectional microphone anywhere near you and your instrument. In a noisy area, you will want to place the microphone close to you and your instrument, but also as far as you can from external noise such as space heaters, air conditioners, and noisy pets or family members.
Bi-Directional (Figure 8)
The Bi-Directional or Figure 8 pickup pattern is a common pickup pattern with side address podcasting microphones (more on this later), as well as an option on higher end USB or XLR condenser microphones, such as the Blue Yeti and RØDE K2.
Its name comes from the figure 8 shape made by the polar diagram. In a 3D space, this would look like two large eggs or ovaloids in front and behind the microphone capsule. This means that bi-directional microphones pick up the most sound in front (0 degrees) and behind (180 degrees) the capsule, and reject the most outside noise from the sides (90 and 270 degrees).
This pickup pattern is best used for recording audio content like podcast interviews where the microphone is placed directly between two face-to face speakers. Because of the nature of bi-directional microphones, it's not specifically suited for online music lessons unless your teaching/practice room is setup in such a way that bi-directional pickup will benefit from it.
Front Address or Side Address?
Aside from the microphone's pickup pattern, it is also important to know if your microphone is a Front Address or Side Address microphone. This refers to how the microphone should be physically aimed for optimal performance.
A Front Address microphone (also known as Top Address or End Address) is the most common type of microphone construction. These microphones look like they should be aimed in the direction that they are built. For example, you always aim the top of a handheld, cardioid karaoke microphone towards your face or mouth. The ends of overhead pencil microphones commonly used in orchestras and choir recording are normally aimed downward and towards the band or choir.
A Side Address microphone picks up sound from the side of the microphone. These are common in certain USB microphones (the Blue Yeti is actually a side address microphone), as well as various studio and broadcasting microphones. Normally these microphones are placed on a stand or adjustable arm, and the top/end of the microphone points upward. Therefore, the side of the microphone is aimed towards the sound source. If you try to aim these microphones in the same manner as your usual Front Address, your intended recording volume will be much lower and will be more prone to outside noise due to incorrect aiming.