Dialogue Components and how Sound Behaves

Imagine hitting a bunch of billiard balls; some go into the intended pocket, others ricochet off the cushions before finding their way into pockets. This illustrates the behavior of sound when you record a voice in a moderately sound-reflective room. The voice is signal and what accompanies it is reflected or reverberant sound (Figure 11-1). That is, some of the voice goes straight to the microphone, but some of it radiates outward and bounces off the floor, ceiling, walls, and that table in front of the speaker before reaching the mike. Reverb sound, making a longer journey, arrives fractionally later. Direct and reverb sound then combine at the microphone to muddy the clarity of the original. People think, “Oh, let’s fix it in the sound mix,” but once combined, sounds are no more separable than the eggs in an omelet.

In Figure 11-1, a person sits in a room talking to camera. The microphone is picking up not just signal and reverb but also background presence or ambient sound. Also called atmosphere, it might include distant traffic, the hum of a refrigerator, a dog barking, or in summer the whir of air conditioning. Ideal dialogue recordings have lots of signal (what you want) and very little noise (everything else). The world is not ideal for sound recordists, but there’s always something you can do to improve matters. That mike in Figure 11-1 could go a lot closer to the speaker. Moving it won’t affect ambience or reverb levels much, but it will dramatically raise the direct signal level in relation to them. For this reason, avoid using a deck mike (one mounted on the camera) if you can work with a partner using a boom or fishpole to get the mike in close (Figure 11-2). Reasons to abandon the deck mike are:

• It’s nearly always too far away from source sounds.
• It points only along the camera axis when important sound in a discussion, say, will often come from off-axis.
• It’s nicely placed to pick up the whine of the zoom motor and the bumping sounds of your hands fumbling for the cam-corder controls.

FIGURE 11-1 Diagram representing a film interview and the three types of sound present in any recording situation: direct, reverberant, and ambient.

We’ll look at boom handling techniques a little later.

On-axis sound (also called on-mike sound) is sound arriving down the mike’s most receptive axis. Off-axis or off-mike sound arrives from other axes. Directional mikes favor on-axis sound and discriminate against that arriving off-axis. Most of the reverb and ambience in Figure 11-1 arrives off-axis, so the right mike can discriminate against them.

FIGURE 11-2 A microphone on a fishpole can reach over people and equipment and get close to the sound source. Carbon-fiber models are the lightest. (Photo courtesy of K-TEK.)

Sound perspective is the aural sensation of changing distances when a sound source (person, helicopter, horse) moves around.

A resonant space is one that has a note to which the room spontaneously resonates. You’ll know this from singing in your shower and finding a frequency at which the room starts ringing and augmenting your voice. Resonances and sound reflectivity are bad news to sound recordists, as are noisy locations.

Balanced and Unbalanced Inputs

Professional mikes use balanced line cables with sturdy XLR connectors that lock into their sockets, and they use noise-canceling three-wire connections between mike and recorder (Figure 11-3). With these you can use 10- to 20-foot or longer microphone cables without picking up electrical interference. Consumer equipment uses the two-wire or unbalanced sound connections, easily identifiable by their two-contact jack plugs (Figure 11-4). These allow only short cable runs before noise and interference set in. Also, because mini-jack sockets are attached to camcorder circuit boards, a single yank on the cord can do untold damage. Even in kinder circumstances, jack sockets quickly become unreliable unless you provide cable strain relief. This means anchoring the headphone or mike cable to the camera body so handling stresses do not reach the plug or its socket (Figure 11-5).

FIGURE 11-3 XLR plug on three-wire balanced cable and the locking socket it goes into.

FIGURE 11-4 Phone jack and mini-jack plugs. Two-connector unbalanced lines like these tend to pick up hum and other electrical interference.

FIGURE 11-5 How a strain-relief measure protects a plug and its socket from the inevitable tugs on the cable.

Choosing Manual or Automatic Sound Level

Whenever possible, set sound levels manually. This means, during a test, lowering the recording level as it registers on the volume unit (VU) meter or bar graph until no peak sound surpasses, say,–6 decibels. Check what your camcorder manual recommends and make test recordings of loud transient sounds such as hand claps or door slams to pinpoint the threshold where distortion sets in.

Volume Unit (VU) Meters

In the typical stereo VU meters in Figure 11-6, the numbers run counterintuitively from minus to plus quantities. Low sound levels register as high minus decibel (dB) numbers. Then as sound levels rise, the safe or sound saturation point peaks at 0 dB. Beyond that you enter the red or danger zone of + dB levels where distortion can ruin the recording. Here beginneth wailing and gnashing of teeth.

Averaging and Peaking

Analog sound—the precursor to digital recording—was quite forgiving during overloads, but peaks beyond 0 dB in digital recording usually distort badly. Be aware that unless your equipment has a peak reading meter, your VU meter is averaging incoming signals and thus hiding the awful truth from the unsuspecting user. By the time you’ve seen the peak red light come on, the damage is done. To guard against this, set levels for averaging meters to peak at–6 dB.

FIGURE 11-6 Typical sound volume unit (VU) meter layout. Camcorders usually supply a moving bar graph in the viewfinder.

FIGURE 11-7 Two-channel input box that can handle either microphones or amplifier (line) input. (Photo courtesy of BeachTek, Inc.)

Automatic Level

Using automatic sound-level spares you distortion, but during long gaps in an oral memoir, for example, the recording level may hunt—that is, record at louder and louder levels until your subject speaks again. The reason is that electronic circuitry has zero intelligence and does its job strictly according to level. Use automatic level whenever you are in a chaotic situation with soft sound punctuated by, say, door slams, screaming revelers, or other loud and transient peaks.

Microphone Input Boxes

If your camcorder has a single mini-jack mike input, add one of the excellent proprietary input boxes (Figure 11-7). Because it is clamped under the camera body, the box and its beefy XLR sockets safely absorb the inevitable cable-handling stresses. Now you can plug in two balanced-line microphones and even adjust each for level. As the illustration shows, the box’s output plugs into the camcorder mike input using a stereo (three-connector) mini-plug on a pigtail lead. Be aware that condenser microphones—in particular, shotgun mikes—either run on inbuilt batteries or draw current from phantom power supplied by some (but by no means all) camcorders and input adapter boxes. Phantom power is not as exciting it sounds. It’s a tiny current at 48 volts fed to the mike through two legs of its three-wire cable.

Stereo

Virtually all camcorders have stereo (two-track) recording capability and can accommodate two inputs. If yours makes recordings that are well separated, then you can record, say, two people each wearing a lavalier (chest) microphone and end up with a clean, totally separate track for each. You might, for instance, use a telephone attachment to record a soldier speaking by phone from the Middle East in one channel and in the other his mother speaking into the phone in her front room. Being on separate tracks, you can adjust their levels in the sound mix.

Listen to your Work

Whenever you shoot sound, monitor what you are recording through quality, ear-enclosing headphones (Figure 11-8). Not monitoring, or monitoring with a more stylish substitute like iPod^® earbuds, will land you in trouble.

Handling the Fishpole

Your best sound, as we’ve said, will come from using a directional mike angled on a fishpole. Position it above, below, or to one side of the frame line. Miking from above is preferable because a voice will then be louder than the speaker’s footsteps and body movements. If this causes fishpole shadow problems, try coming in from the side of the frame. If all else fails, point the mike upward from below frame. This is least desirable because it privileges footsteps and body movements over voice levels.

Windscreens and Shock Mounts

Suspend your mike in a rubber shock mount to reduce the transmission of handling sounds to the mike. Figure 11-9 shows a common rubber-band model,

FIGURE 11-8 Videographer wearing ear-enclosing headphones—a necessity for proper sound monitoring. (Photo courtesy of Vinten, a Vitec Group brand.)

FIGURE 11-9 Two types of mike shock mount. The rubber-band type (left) is common but is likely to make sounds of its own. The K-TEK (right) is the more reliable design. (Photo courtesy of K-TEK.)

which I don’t recommend, next to a more reliable design. Shield the mike from air-current interference, even indoors, with a windscreen (Figure 11-10). This is a rigid zeppelin wind guard, and to it you add a fuzzy fur mini-screen or windsock (Figure 11-11) to defeat outdoor air movement. Absent such shielding, air currents shake the mike’s diaphragm and produce earthquake quantities of wind rumble.

FIGURE 11-10 Zeppelin type of microphone windscreen. (Photo courtesy of K-TEK.)

Achieving On-Mike Sound

Getting mikes close to participants without causing shadows takes coordination among recordist, camera operator, and director. Handheld sequences are the most challenging because the mike must not edge into the frame. Miking from a safe distance isn’t an option because S:R ratios decline precipitously and you may wind up with extreme noise and intelligibility problems.

FIGURE 11-11 Fuzzy fur mini-screen, or windsock, covering zeppelin. (Photo courtesy of K-TEK.)

Relationship of Recordist to Camera

Experienced, on-the-ball recordists constantly scan the subject, the likely edge of frame, and the camera operator for telling facial expressions or hand signals. These might signify, “Watch out, I’m going to swing in your direction,” or “Back off—mike’s edging into frame.” Usually the recordist stands a little ahead and to the left of the camera, in the camera operator’s left-eye sightline (Figure 11-12). The goal is to position the mike as close as possible to, and pointed at, each new speaker while staying just out of frame. Staying close to the sound axes of moving participants, yet keeping the mike from edging into frame, requires the recordist to predict who, between camera and participants, will move next and what direction they may take. With experience, camera and sound people learn to work in perfect balletic harmony—and even to exchange hand or eye signals during the take. It’s a joy to watch.

Sometimes the recordist lifts the mike over the camera to allow the operator to pan left or back away from the subject. If a new sound axis calls for it, the recordist crosses the shooting axis behind the camera and positions the mike temporarily over the camera on the right (Figure 11-13). All the while the recordist tries to maintain eye contact with the camera operator—a choreography all to be managed in silence. Often the sound operator will lightly touch the camera operator’s shoulder to ensure they don’t collide or stumble over objects. Sometimes the director also uses touch to assist.

FIGURE 11-12 Diagram showing typical sound recordist’s positioning during mobile shooting. (Also see photo in Chapter 9, Figure 9-13.)

The ultimate challenge to the mobile documentary unit is a rapidly moving subject who whirls through a street market and then jumps into a taxi, all the while chatting to the camera. Keeping all this nicely framed on the screen and with no sign of the unit’s frantic activity will stretch a crew to its limits, particularly when two extra people silently cram themselves and their equipment around a surprised taxi driver.

FIGURE 11-13 The recordist must sometimes cross behind the camera, mike still in place, to angle in from the right side of frame. The camera body may now block eyeline exchanges with the camera operator.

When Sound and Picture Subjects Diverge

In a group scene, the camera may dwell on someone’s telling expression. Someone new starts speaking, so the mike cannot stay with the camera subject but must swing immediately toward the new sound subject (Figure 11-14). Mike placement can be:

• From either side of the frame, depending on which way speakers are facing.
• Above the frame, depending on sound needs and lighting (that is, shadow) considerations; absent shadow problems, miking from above is preferable.
• Below the frame when all else is impracticable.

Recordist as Safety Monitor

In a two-person crew when the camera must track backward, the recordist lightly touches the operator’s back with her free hand to signal, “I’m here and I’m watching for your safety.” This touch includes gentle steering—overzealous would rock the camera—so the operator clears furniture or doorways without looking around. It’s quite marvelous to watch an experienced crew cover all eventualities with balletic precision and confidence. This is something you only get from much practice.

FIGURE 11-14 The camera shoots a reaction shot while sound covers the off-camera speaker. In everyday life, our eyes and ears often unconsciously separate like this.

Power Supplies

Many mikes require battery power, so carry backups and only use the alkaline variety. Other varieties run down and excrete a corrosive mess into the mike body. Some professional mikes require phantom power through a small voltage fed from the recorder via the mike cable. Many nonprofessional camcorders now supply it, but if a mike mysteriously refuses to function, then check the manual to see whether yours is not among them.

Pickup Patterns

Inexpensive microphones, as we have said, don’t necessarily do a poor job—you just have to use them judiciously. Most important is to know sound pickup patterns for each type. The representation in Figure 11-15 of the pickup patterns of three different mikes indicates where, as you circle each type of mike, you’d expect to place a noise-emitting object (think of a cicada in mating mood!) to maintain an equal level recording. The omnidirectional mike is the simplest; it picks up sound equally from all around, so you’d place your cicada at the same distance all around it. To differing degrees the other mike types favor on-axis sound and discriminate that which is off axis. Here are some generalizations:

• Omnidirectional mikes give the most pleasing voice reproduction but tend to indiscriminately pick up unwanted sound reflected by surrounding surfaces.
• A directional mike (also called a cardioid because of its heart-shaped pickup pattern) helps cut down on off-axis reverberant and background noise. In practical terms this means that pointing the mike’s axis at a speaker improves his S:N ratio.

FIGURE 11-15 Diagram indicating microphone pickup pattern differences among: (1) shotgun, (2) cardioid, and (3) omnidirectional mikes. A scientifically accurate polar pattern is shown in Chapter 27, Location Sound.

The hypercardioid or shotgun mike (so-called due to its shape and menacing appearance; Figure 11-16) does the best job of discrimination. A favorite in documentary and electronic newsgathering (ENG) work, it is especially practical in noisy situations. Its drawback is a slight loss of sound warmth and fidelity. More than most mikes, it requires astute handling so it stays out of shot, doesn’t cast shadows, and yet still points at the right speaker in a group. A BBC news crew using a shotgun mike in the jungle was astonished to find it had taken a prisoner during the Vietnam War. Many mikes have small switches that allow you to “roll off” (attenuate, reduce) a particular band of frequencies. A “lo-cut” is useful because it reduces traffic rumble during street dialogue scenes.

FIGURE 11-16 Shure^® SM89, an affordable shotgun microphone with two selectable low-cut frequencies. (Photo courtesy of Shure, Inc.)

FIGURE 11-17 Wire looped under lavalier clip as strain protection for a delicate mike.

Use lavalier or lapel mikes (Figure 11-17) for interviews or speech recording in noisy surroundings. When clipping the mike in place, anchor its cord as the photo shows so as to leave a free loop under the mike. Then, if the cord is touched or yanked, handling noise or damage won’t reach the mike. Participants wear these tiny omnidirectional mikes under upper clothing so they stay exceptionally close to the signal (speech) source. Place them at least a hand’s breadth away from a speaker’s chin or sound levels will vary too much when the speaker’s head swivels. Since you’ll need one lavalier per speaker, multiple speakers require a location mixer (see Part 7: Advanced Production Issues, Chapter 27, Advanced Location Sound).

Body mikes are prone to picking up clothing rustles and body movements—especially when the user wears manmade fibers. These generate static electricity, which sounds thunderous. Ask participants to wear natural fibers, but if they don’t, place adhesive tape between the mike and the offending surface. Lavaliers also excel at amplifying the intestinal activity that follows dining, and they love loose dentures in the elderly.

Lavalier mikes give lovely voice quality but lack all sense of sound perspective— the aural sensation of changing distances that we’re so used to. Staying close to the speaker’s mouth, they pick up little reverberant coloration and thus give no aural perspective changes even when a speaker is visibly on the move. You can emulate perspective changes later in the sound mix if you really need to.

Wireless Mikes

When they work, they’re wonderful. Connect a lavalier mike to a personal radio transmitter, clip a small radio receiver to the camera, and, presto, everyone has complete mobility. Ah, but they have drawbacks. Like mobile telephones, even the most expensive may fade or pull in taxi radios. Be warned, too, that participants forget they are wearing them and may, without your intervention, broadcast their visits to the bathroom. A court used a recording made inadvertently by some of my students at a demonstration as evidence to indict a duplicitous police chief. See Chapter 27, Advanced Location Sound, for wireless mike recommendations.

Wired Mikes

A wired lavalier, though limiting to your subject’s mobility, is trouble-free compared with its wireless brethren. You hide the cable in the participant’s clothing so it emerges from a pants leg or skirt bottom. Be aware that here, too, people forget they’re wearing them. They walk away until, quite literally, they reach the end of their tether.

Ambience in Films

In a finished film, the audience accepts some ambient atmosphere as part of each new sequence’s reality. The ear identifies the ambient content, then screens it out. Such easy adaptation deteriorates, however, when irritating and intrusive “atmos” changes occur on cuts from angle to angle. To cure this, backgrounds have to be built and adjusted in editing to create a seamless auditory experience. This is how we experience ambience in everyday life, so we expect no less in films.

Location Procedure

Before calling for a wrap at any location, whether interior or exterior, let the crew record a presence track (also known as atmosphere, room tone, or buzz track). Do this in every location, every shooting day, because each occasion has its own changing ambience. The procedure is simple:

1. The recordist calls, “Everyone freeze: We need a presence track!”
2. Everyone stands completely silent.
3. The recordist makes a recording of the ambient sound from the current mike position, disturbing nothing in the location.
4. The recordist calls “Cut!” and everyone jumps into action, wrapping up for that location.

Sounds on the Set

During takes, the crew and any onlookers must be as stationary and silent as possible, and the camera must make no sound that the mike can pick up. Fluorescents like to buzz, filament lamps can hum, and pets come to life at inopportune moments. Mike cables placed in parallel with power cables may produce electrical interference through induction, and sometimes very long mike cables pull in cheery DJs via radiofrequency (RF) interference. Elevator equipment can generate alternating current magnetic fields, and the most mysterious hum sometimes proves to come from something on the floor above or below. Every situation has some degree of remedy, once you have located the cause.

Sound Reconstruction

In film sound, you often have to provide what is appropriate and not what was present. To be true in spirit, you reconstruct some sound during postproduction. At the exquisite nature center near where I live in Chicago, there are deer, wildflowers, some prairie, a lake with a heron or two, and lots of wild birds. I have daydreamed about filming a year-long cycle of life there, but it’s under the flight path for the world’s busiest airport, and vehicles roar past only two blocks away. I would need to reconstruct every atmosphere and sync sound because no audience could concentrate on lyrically backlit meadow grasses to the ominous whine of sinking jetliners.