Choosing the Right Microphone Polar Pattern for Quality Sound

The quality of sound captured in any recording or amplification scenario hinges significantly on the choice of microphone, particularly its polar pattern. This characteristic dictates how a microphone picks up sound from various directions, which can dramatically affect the clarity and fidelity of audio recordings.

Understanding these patterns is crucial for anyone involved in audio work, whether it’s in music production, broadcasting, podcasting, or filmmaking. The right selection can mean the difference between a professional-sounding recording and one plagued by unwanted noise or poor sound quality.

Overview of Microphone Polar Patterns

Microphone polar patterns are an essential aspect of sound recording and amplification, serving as a roadmap for how microphones capture sound from different angles. These patterns are integral to tailoring the pickup of sound to the specific requirements of a recording situation, ensuring that the desired audio is captured while minimizing noise and feedback.

Cardioid Patterns

Cardioid microphones are named for their heart-shaped pattern of sensitivity. They are most responsive to sound coming from the front and are less sensitive to sound from the sides and rear. This makes them ideal for isolating a sound source in environments where there is potential for background noise. The Shure SM58, a staple in live vocal performances since its introduction in 1966, is a classic example of a cardioid microphone. Cardioid patterns are further divided into subcategories, such as supercardioid and hypercardioid, which offer tighter front-end sensitivity with narrower angles of sound acceptance. These variations provide more directional control but can also pick up some sound from the rear, which is important to consider in microphone placement.

Omnidirectional Patterns

Omnidirectional microphones capture sound equally from all directions. They do not discriminate between sounds from different angles, making them versatile in capturing ambient noise and ensuring a natural blend of sound in a recording. The DPA 4006, a reference standard microphone for acoustic measurement and recording since its release, exemplifies the omnidirectional pattern’s utility in capturing sound with a true-to-life representation. These microphones are particularly useful in situations where the sound source moves around the microphone or when capturing the atmosphere of a space is desired. However, they can be prone to feedback in live sound reinforcement situations.

Figure-8 Patterns

Figure-8 or bidirectional microphones pick up sound from the front and rear while rejecting sound from the sides. This pattern is characteristic of ribbon microphones, such as the Royer Labs R-121, which has been a favorite for miking guitar amplifiers and brass instruments since its introduction in 1998. Figure-8 microphones are excellent for recording two sources simultaneously, like a duet, or for use in mid-side (MS) stereo recording techniques where side rejection is beneficial. They are also useful in controlled studio environments to capture the direct sound of an instrument while also picking up room reflections from the opposite direction, adding depth to the recording.

Shotgun Patterns

Shotgun microphones feature a highly directional pattern that is designed to pick up sound from a narrow area in the front, rejecting sound from the sides and rear almost completely. This makes them ideal for use in film and television production where they can be aimed at a sound source from a distance, such as the Sennheiser MKH 416, which has been a mainstay in the industry since the 1970s. Their long, tube-like design is responsible for their directionality, which is particularly useful in noisy environments or when the microphone cannot be placed close to the sound source. However, their highly directional nature requires precise aiming and handling to avoid missing the intended audio.

Selecting the Right Microphone

The selection of the appropriate microphone for a given application is a nuanced decision that hinges on understanding the environment and the specific audio needs of the project. The polar pattern plays a significant role in this choice, as it influences how sound is captured and can either enhance the desired audio or introduce challenges that must be managed.

Studio Recording

In a studio setting, the acoustics are typically controlled, allowing for a range of microphone polar patterns to be used effectively. Cardioid microphones are often favored for vocal recordings due to their ability to focus on the singer and reduce the pickup of ambient noise. For instruments, the choice may vary; omnidirectional microphones can be excellent for capturing the natural resonance of acoustic instruments in a well-treated room. Figure-8 microphones are useful for capturing the direct sound and room acoustics simultaneously or for recording two sources facing each other. The selection process should consider the instrument’s sonic characteristics, the desired sound, and the room’s acoustics. For example, a Neumann U87, renowned for its versatility and introduced in 1967, can be employed in various studio applications due to its multiple polar pattern options.

Live Performances

During live performances, the primary concern is often the management of feedback and the isolation of the desired sound source from ambient noise. Cardioid and its tighter variants, supercardioid and hypercardioid, are commonly used due to their directional nature, which helps to avoid the pickup of sound from monitors and audience noise. For example, the Audio-Technica AE6100, a hypercardioid dynamic microphone, is designed to deliver clear vocals with high feedback rejection. The choice of microphone may also be influenced by the need for mobility and durability on stage, as well as the specific requirements of the performance space. Omnidirectional microphones are generally less favored in live settings due to their susceptibility to feedback, but they may be used for area miking or in situations where sound from all directions needs to be captured, such as with choirs or orchestras.

Field Recording

Field recording presents a unique set of challenges, often requiring microphones that can handle a variety of unpredictable acoustic environments. Shotgun microphones are particularly useful in this context due to their highly directional pickup pattern, which is ideal for capturing specific sound sources in noisy or outdoor environments. For example, the Rode NTG3, known for its durability and weather resistance, is a popular choice among field recordists. Omnidirectional microphones may also be used to capture ambient sounds and environmental atmospheres with a natural quality. The choice of microphone for field recording should also take into account factors such as the microphone’s sensitivity, self-noise, and the need for wind protection.

Film and TV Production

In film and TV production, the clarity and directionality of the audio capture are paramount. Shotgun microphones are frequently used on boom poles or mounted on cameras to capture dialogue clearly while minimizing background noise. The Sennheiser MKH 416, mentioned earlier, is a prime example of a shotgun microphone that excels in these applications. Lavalier microphones, which are small and can be clipped to clothing, are also commonly used for their discreet appearance and ability to capture close-miked speech. These often feature omnidirectional patterns, such as the Countryman B6, which has been a discreet solution for film and television since its release, due to their less conspicuous presence and consistent pickup even when the subject moves. The selection of microphones for this field also involves considerations of wireless transmission quality and the potential for interference, as well as the adaptability of the microphone to various filming conditions.

Tips for Optimizing Microphone Use

To optimize microphone use, one must first ensure proper placement relative to the sound source. This involves considering the distance and angle at which the microphone is positioned to capture the best possible sound. For instance, placing a microphone too close to an acoustic guitar might result in an exaggerated bass response due to the proximity effect, while positioning it too far could introduce too much room ambience. Experimenting with placement can help in finding the sweet spot where the microphone captures a balanced and true representation of the source.

The acoustics of the recording environment also play a significant role in the quality of the captured sound. Even the most suitable microphone can yield subpar results if the room has poor acoustics. Treating the space with acoustic panels or diffusers can help to control reflections and reduce standing waves, leading to a cleaner and more focused recording. Additionally, using pop filters for vocal recordings can prevent plosives from distorting the audio, ensuring a clear and professional result.

Maintaining the microphone and its accessories is another aspect that should not be overlooked. Regularly checking cables for wear and tear, ensuring that stands are stable and secure, and storing microphones properly when not in use can prevent technical issues that might compromise the recording process. It’s also beneficial to familiarize oneself with the microphone’s specifications, such as its frequency response and maximum SPL handling, to use it within its optimal operating range.