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the sounds of your characters with your separately recorded background walla, and have full control over the loudness of the background, letting you mix the background to more easily hear your foreground characters.
Similarly, any other sounds—doorknobs, car doors opening, windows breaking—can be added later, during a process called foley (named for Jack Foley, the man who pioneered the technique). Foley is simply the process of recording all of the other incidental sounds that your scene needs and mixing them in during your final sound mix.
Recording good audio requires a lot of preparation, and it begins with selecting the right microphone.
Microphones
Although your video camera has a built-in microphone, you shouldn’t use it for most feature and documentary work. On-camera mics are typically low quality and produce tinny sound recorded from all directions. In addition, because of their location on the camera, they frequently pick up camera noise such as motors and hand movements (see Figure 8.2). Consequently, to record good audio, you’ll want to buy or rent one or more high-quality microphones, which you will connect to your camera or to a separate audio recorder such as the Fostex FR-2, as shown in Figure 8.1.
Different types of microphones are designed for different recording situations, so your choice of microphone will be based on matching microphone characteristics to your shooting needs.
Figure 8.1
The Fostex FR-2 audio recorder.
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What a Mic Hears
Just as different lenses have different angles of view—some wider, some narrower—that define what they will see, microphones have different “directional” characteristics that define what they will hear (see Figures 8.2 and 8.3). The directional “coverage” of the mic that you choose will have a lot to do with both the content and quality of your recorded sound.
Figure 8.2
Higher-quality camcorders like this Panasonic HVX200 typically have a built-in directional microphone.
Figure 8.3
Even if your camera has a decent built-in microphone, you still may want to add a higher-quality, shotgun mic like this one from Rode to the mic mount on your camera.
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Omnidirectional Mics
As their name implies, omnidirectional mics pick up sounds from all directions. While this might seem like a good idea for recording the sound of an entire room, omnidirectional mics are often not practical. With their wide coverage, omni mics can pick up far more sound than you might want, including camera noise (and camera operator noise!), as well as ambient sounds such as passing cars or people. Because they listen in all directions, omni mics tend to record echoes within the room, which makes for a much more “boomy” sound.
Omnidirectional mics work well if they are held close to the subject of the sound—within 12 inches or so—because the subject tends to overpower any background sound. However, keeping a mic in this position can be very difficult, particularly if you want it hidden, and especially if your subject is moving.
On the positive side, omnidirectional mics have a low sensitivity to wind and breath sounds, and many provide a “shaped” response that boosts higher-frequency sounds while dampening lower, rumbling sounds. Shaped-response mics are good for preserving the sound of a voice that is being recorded against loud sounds such as traffic or construction.
Unidirectional Mics
Unidirectional (or just “directional”) mics, as you might expect, pick up sound from one direction. Because you can point a unidirectional mic at a particular subject, they are well suited to feature and documentary production, as they allow you to selectively record a particular person or event. Moreover, because a directional mic can be farther from the recording subject than an omnidirectional mic can, they are better suited to some feature production sets, where keeping a mic close to the subject is difficult. Some directional mics are more directional than others, and which type to choose depends on your shooting task.
Most directional mics are sensitive to sound in a cardioid pattern (so named because it looks vaguely heart shaped—see Figure 8.4). A cardioid microphone is more sensitive to sound coming from the front of the mic, and typically attenuates, or drops off, sounds around the sides of the mic. Typically, a cardioid pattern is wide enough that a cardioid mic placed more than seven or eight feet from its subject will pick up unwanted sounds.
A supercardioid mic has a tighter pickup pattern than a cardioid and is similar to the pickup pattern of the human ear. Supercardioid mics provide good results when used at a distance of 6 to 15 feet from the subject.
Figure 8.4
The cardioid patterns for an omnidirectional and a supercardioid mic.
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Finally, hypercardioid mics have an even narrower pickup pattern that rejects most sounds that are “off-axis” from the direction the mic is pointed. Hypercardioids are, in fact, so directional that they can be somewhat difficult to use. If they stray even a little from their subject, they will not pick up the desired sound. You’ll need a diligent mic operator to use a hypercardioid mic.
Contrary to common sense, it’s the holes on a microphone that make it more or less directional. Take a look at a typical handheld or clip-on omnidirectional mic. You’ll see that most of the holes in the microphone’s case are in the very top of the mic, with just a few holes around the sides. Now look at a typical hypercardioid mic and you’ll see a very long tube riddled with holes along its entire length. What’s the deal?
The holes in a directional mic cause the sounds coming in from the sides of the mic to cancel each other out, leaving only the sounds from the front (and sometimes, back). In fact, you can turn a hypercardioid mic into an omnidirectional mic simply by covering up the holes along the sides (see Figure 8.5).
If you can’t afford multiple mics or arrange for a boom operator on your shoot (more on this later), and you need to shoot dialogue scenes, then an omnidirectional mic will be the best choice. Ideally, though, you’ll want a mic with a supercardioid pattern, and the personnel and equipment to use it right. Later in this chapter, we’ll discuss how to mic your scene.
Most microphones come with a coverage chart that indicates the directional pattern of the microphone and how different parts of the field of coverage respond to different frequencies (see Figure 8.6). Although interesting, don’t lose any sleep over trying to understand these charts. Most mics are clearly rated as cardioid, supercardioid, or hypercardioid.
Hands Off That Mic!
Because a mic’s directional characteristics can be affected by the way you handle the mic, be very careful when attaching a mic to a stand or pole with a clamp or tape (or when holding a mic in your hand). Be certain you don’t cover up any of the holes in the mic’s case. Similarly, don’t think that you can make a mic more directional by cupping your hands around the front of the mic.
Figure 8.5
Extremely directional mics such as this one from Azden are ideal for mounting on a boom or fishpole or, in a pinch, mounting on the top of your camera. It is the holes in the side of the mic that give its directional qualities.