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Tools of the Trade, Part 3

Before we look at the next section, which discusses Polar Patterns, wrap your head around this:

Basically, there is no such thing as a “zoom” mic. The most common shotgun mic’s purpose is to “collect” sounds from the front of the capsule. They use phase cancellation and rejection ports on the side and rear to achieve this result of directionality. Yes, technically that’s correct, but it’s often complicated marketing jargon used by mic companies to convince you that their product is better and that you should buy it.

I’m not going to assume that most of you reading this have prior knowledge. Instead, I want to give you simpler references, make you feel like you can learn and actually go out and do this! Therefore, I will use film analogy to cement both microphone types and patterns. So, here is how I distinguish the functions.

Much like we have prime lenses that have faster or slower aperture speeds and are susceptible to light conditions, we have also have dynamic, electret condensers and condensers that react faster or slower to sound sensitivity and volume.

In film, we also have the “coverage” of lenses and camera sensors. Think of frame coverage from an 11mm wide-angle lens to a 85mm portrait lens, primes and zooms or the differences between a micro 4/3s and a crop censor to a full frame image camera. Well, now apply that same concept of “focal length” or “coverage” to the various polar patterns that microphones offer in the ability to pick up or capture the directionality of sound if we could see it.

So now let’s look at some common Polar Patterns, literally.

First, I’d like to thank my colleague and editor, Mike Crick, for the following illustrations. I specified the importance in simplicity of polar patterns in application.

In these pictures, I have placed an individual (being the sound source, ie. dialogue/speech) at the upper end of a square room and stationed a mic consistently in the middle of the room in all 4 images. This is to illustrate the directionality and functionality of various polar patterns.

So, by simply moving along the “proximity” grid line, closer or further to the sound source, you achieve more or less level. This also indicates the “reach” of each polar pattern. The polar pattern remains consistent in each instance, but the timbre of your sound will change slightly as it is now susceptible to acoustical reflection, absorption and diffusion because of the proximity of the walls. Check out my R.A.D acronym in part 1.

Figure 1

Figure 2

Figure 3

Figure 4

Polar Pattern Characteristics and Applications

Omni-Directional (also known as non directional) (Figure 1) mics pick up sound from all directions in an almost 360 degree spherical shape. In theory, omni type microphones eliminate directionality and can also be regarded as “transparent” or “pure” in which sound colouration is minimised.

Mics that employ this polar pattern are generally lavaliere mics, both wired and wireless. Some handheld mics, for Electronic News Gathering, also use this particular polar pattern.

Practical Applications and Tips:

• Excellent for exterior scenes where echo or reflections are not an issue. Even with the 360 degree pick up pattern and close proximity to the subject, the signal will be greater than the extraneous noise bleed.

• Also ideal in a controlled environment or treated sound stage where multiple actors have to be mic’d for dialogue.

• Easy to conceal on an actor and creates “mobility” when a wide shot does not permit for a boom mic. Sound is also consistent when the actor moves his/her head around while speaking.

• Not ideal in very tight spaces where the pickup pattern is susceptible to delay or ambience. The omni pattern can also pick up extraneous noise bleed and room reverberance while not properly separating dialogue from ambience.

Cardioid (Figure 2)

The cardioid pattern is the most common of directional mics and is called cardioid because of its inverted heart shape like pattern sensitivity or “focal range” to sound.

Cardioids are also the most misunderstood and underutilized pattern in independent film and broadcast. They are widely used in music production, Foley and sound design. The studio cardioid condenser is the staple of any audio engineer’s diet. Contrary to popular belief, the narrow or omni pick up patterns are not the only means of recording dialogue for interior scenes. Cardioids can be considered a specialty pattern in film and TV. They usually exist as extra short shotguns, but are described as small diaphragm condenser mics in audio engineering terms. They are wider in “focal point” than standard shotgun mics with narrower patterns. Cardioid patterns can also be found on some lav mics.

Practical Applications and Tips:

• Excellent for interior scenes, low ceilings and confined spaces where echo and ambience is an issue.

• Does a great job of minimising echoes and creates more natural sounding dialogue with amazing, clear and pristine results.

• Best choice for car interiors. By placing or concealing cardioid lavs or smaller cardioid mics on sun visors or headrests in close proximity to the actor’s head, the mic will yield clearer and richer dialogue. Experiment with your placement and remember, cardioids have excellent rear axis rejection, wide enough to sound natural and are not too open like an omni. With an omni, you hear everything from engine noise to wind.

• These patterns don’t have much reach or side rejection, but they do have a wider pattern that can cover two people with no need to swivel your boom. Great for close ups and medium close ups.

• Ideal pattern when “planting” or hiding mics amongst props within a set.

• Excellent choice for recording sounds and effects in Foley applications.

Hyper Cardioid (Figure 3)

A polar pattern that is more narrow and tighter in sensitivity when compared to the cardioid pattern. This polar pattern has more side rejection, more reach and a small “lobe” of sensitivity at the rear. This pattern is commonly found in short to medium shotgun mics.

This polar pattern is perhaps the most versatile and consistent while keeping “mobile” and recording dialogue indoors or outdoors.

Practical Applications and Tips:

• A mic with this pattern will cover your general audio recording needs if you’re on a budget or if you need to make an initial purchase.

• A good general starting point as a primary microphone pattern, while blending or matching all your other mics and pattern types to this one.

• Handy for general mono recordings either in the field or in the studio for Additional Dialogue Replacement.

• Mics available with these patterns are available in small form factors, which are light, portable and convenient.

• Mics available with these patterns are small enough to mount on cameras if you don’t have a dedicated boom operator or sound recordist.

• Has a more prominent “focal point” and reach compared to the cardioids. This can accentuate sound from behind the sound source when held vertically. Think of a higher F-stop on a lens, which throws everything else in the background more in focus.

Super Cardioid (Figure 4)

An extremely tight pattern as far as sound sensitivity is concerned. The super cardioid has the highest possible directivity and is sometimes listed as a line + gradient. It also has a narrower lobe on the rear, which picks up some sound. This polar pattern is usually found on long to extra-long shotgun mics.

Practical Applications and Tips:

• Fantastic for outdoor applications and noisy exteriors.

• Superior reach or “focal length,” especially when you cannot get the mic close to the sound source.

• Ideal for wider framed shots.

• Negative characteristic of extreme narrow pattern means that a lot of ancillary sound is picked up from the rear of the pattern.

• If shooting indoors, any set, crew, sound activity and room echo reverberant properties will also be picked up.

• Make sure to observe my R.A.D acronym argument when using super-cardioid related mics indoors.

• Remember to use these polar pattern type mics (ie. long and extra-long shotguns) with adequate support systems such as suspension mounts, blimps, zeppelins, windscreens and wind jammers, etc. to minimize wind and handling noise.

 

 

Join the conversation

3 Responses to “Tools of the Trade, Part 3”

  1. ted on November 29th, 2011 8:09 pm

    “The super cardioid has the highest possible directivity and is sometimes listed as a line + gradient.”

    I thought “line + gradient” usually just referred to a bass rolloff switch some microphones include to cut down on wind noise?

  2. Clinton Harn on November 30th, 2011 8:19 am

     

    Hi Ted,

    Shotgun mics are also generally refered to as “Line” Microphones, a design, which utilizes an interference tube in front of the element to enable more cancellation of sound arriving from the sides. Hence, you see ports or “grills” on the side of the mic. This, combined with a directional (“gradient”) element, increases cancellation at the rear of the mic as well.

     

    As for various length shotgun or “Line” mics, the longer it’s design, the narrower the acceptance angle becomes, and an increase in it’s working distance is acheived.

     

    The bass rolloff switch, often refered to as a hi-pass or low-cut filter, is an optional switch found, or internally implemented & spec’ed on some shotgun mics to remove lower frequencies generally below 100Hz.

     

    It attempts to eliminate low end rumble or extraneous noise, but does not prevent or cut down wind from exerting the diaphram of the mic. You need to use Windshields, wind jammers or “fluffies” to minimize wind induced noise.

     

    Hope that answers your questions and thank you for reading my article. Feel free to contact me should you have further questions. Best Regards, Clinton

  3. Juan Gallego on January 9th, 2014 6:37 am

    Excuse me,and with all due respect as I am no expert but, aren´t Super cardioid and Hyper cardioid polar patterns and characteristics interchanged?

About the Author


A cinematographer, filmmaker, producer and audio recording engineer, Clinton’s peers & colleagues regard him as a “Renaissance” man, as his passion for creative technology has seen him delve into almost every facet of creative & artistic media content. After years of being entrenched & producing work for the music industry, 2013 will finally see Clinton shoot his first full length feature film, which is currently in production, with a 2015 scheduled release. His recent endeavors includes working as camera operator and AC to Rodney Charters ASC, known for lensing numerous TV dramas such as 24, Dallas, Shameless, Roswell, and many more.

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