Sound Reasoning: The Great Outdoors

Have you ever spent hours trying to get a perfect outdoor shot, only to find the audio consists of nothing more than freeway noise, wind and the far off barking of a dog? Don't be discouraged -- clear, quality outdoor audio can be difficult to achieve. But with just a little forethought and the information given here, you can come back with the best possible audio every time, even if the elements conspire against you.

Redundancy
Equipment failure is one of the worst things that can happen on any kind of shoot. When shooting in a studio, if something goes wrong with a piece of equipment there is usually something else around to replace it. But in the great outdoors you have nothing more than what you brought with you. If something stops working, it can bring your shoot to a dead halt.

Most videomakers are under-equipped for outdoor shooting. If you're getting great sound from your expensive directional mike, but your mike cable gives up and it's the only one you have, then what? You'll have to switch to the camcorder mike and risk the drop in sound quality. Or what if the batteries in your expensive directional mike give up and the closest replacements are at a drug store twenty miles away?

You can prevent all of these problems by carrying just a little extra gear. One or even two extra mike cables is a good idea. Consider an extra cable for every two mikes you carry. And be sure to carry an extra mike. Some mikes, especially dynamics, are very tough and seem to last forever. But they can fail, and will always choose to do so when you need them most. It's surprising how many people think that one set of new batteries for each shoot are all that's required and forget that batteries can actually wear out in the middle of the shoot. Extra batteries for condenser and wireless mikes, two sets, provide cheap insurance for your audio.

Try to carry at least one spare of every item you're going to use. If you're just shooting with a camcorder, carry at least a spare external mike, a spare battery and a spare cable.

Mike It
Choice of microphone depends on what you're shooting. You can easily record someone standing still or speaking at a podium with a cabled mike on a stand. But someone walking across a football field presents a different challenge. Probably the worst mike for shooting outdoors is the built in mike in your camcorder. First, you can't disconnect it from the camcorder, making it sound distant from any outdoor sound source. Second, and more importantly, many built in camcorder mikes have omnidirectional pickup patterns. This means they pick up sounds equally from all directions.

Thus traffic on the road behind you may end up just as loud as the talent you're shooting. However, the omnidirectional has its place, especially in quiet locations where a large group of people are exchanging dialog.

Probably the best choice of mike for use on or near the camera are those with unidirectional or supercardioid (highly directional) pickup patterns. By design, these mikes are more sensitive to sounds coming from directly in front of the camcorder. In our previous example, a directional mike would cancel out most of the sound of the traffic behind you. Or have your talent hold a directional mike for even better noise rejection.

Commonly called shotgun mikes, these highly directional mikes can be camcorder mounted, hand held or even mounted on a boom to get them closer to the sound source. Shotgun mikes generally use a small internal battery, so make sure to heed the above warnings and carry extras.

If you don't have a shotgun mike, you might consider using a parabolic reflector--a bowl-like plastic device which surrounds the mike. You mount your mike in front of the reflector pointing back towards its center, and the combination works as an extremely unidirectional mike. Sound comes into the reflector, and is bounced directly into the microphone.

You may have seen someone holding this setup on the sidelines of a national football game--that's how you can hear the referee on the field when he's not carrying a mike. The parabolic reflector will cut out all ambient sound 2except that directly in front of it. But there is a drawback: parabolic reflectors often have a tinny or hollow sound.

Sometimes your speaking talent may be far off in the distance, or framed in such a way that a sound recordist or mike stand would be clearly visible in the shot. Or perhaps the talent's movements will not allow good sound from a handheld mike. In this case, the wireless lavalier mike is an excellent choice. You can hide one completely in the talent's clothing, or clip it inconspicuously to a dark shirt or blouse.

One advantage of the wireless lavalier is that it stays right at the sound source and produces full, strong audio. Because lavalier mikes are impossible to "aim," they use an omnidirectional pattern. Place it too far from your talent's mouth, and it may pick up unwanted sounds. All wireless mikes used outdoors require batteries for the mike as well as the receiver, so once again: carry extra batteries! Wireless mikes are available with different frequencies if you need to use more than one at a time.

All mikes, regardless of type, pick up wind noise when used outdoors. You can minimize this with a wind sock. A wind sock is a cover, usually made of foam, that slips over the front of the mike. They come in all sizes to fit all types of mikes (even tiny lavaliers) and generic ones are cheap. Professional sound recordists use large, furry wind socks called "blimps." While more expensive than a normal foam wind sock, they offer the utmost in wind protection. Either style of wind sock is good insurance on any outdoor shoot.

Mix It Up
Even with a single input on your camcorder it is often desirable to have more than one sound source coming in for recording. Often two people walking closely together in the distance can share one wireless mike. But what about a shot where an announcer in the foreground is speaking into a handheld mike, and twenty yards behind him two football players (both wearing wireless lavaliers) are arguing the finer points of the game? You want all three sound sources on your audio but you only have one input. The answer is the portable audio mixer.

With a portable audio mixer, you can connect multiple sound sources to your one camcorder sound input. This means you can combine (or "mix") the sound from the two arguing football players with the announcer's foreground babble. Portable audio mixers come in many shapes and sizes. The average mixer has four mike inputs and two outputs (for stereo, switchable to mono). They usually offer both A/C and battery power. Need I mention extra batteries again?

One problem with sending a mixer output to a camcorder input is matching signal levels. The camcorder input takes very weak mike level signals. The mixer output, on the other hand, is most often a much stronger line level. Plugging the mixer output directly into the camcorder mike input will cause major distortion in the audio.

Some mixers have a switch which sets the output to a mike level signal, but if yours does not do this, then you must use an attenuator. An attenuator is a device which places a resistor in the line between the camcorder input and the mixer output. This cuts the mixer's output down to a level usable by the camcorder.

Another problem is the built in AGC (automatic gain control) in your camcorder. This circuit automatically sets your audio recording levels. AGC will bring up the volume of noise in the silence between bursts of dialog. In any event, you have to live with it unless your camcorder is top of the line and has its own level controls.

Earphones are one of the most important items you can carry to an outdoor shoot. The only failsafe for everything discussed so far is a good set of earphones. A videomaker will realize this the first time he or she returns from a seemingly good shoot (without earphones) to find no audio on the tape because of a dead battery or bad cable. Earphones would have alerted them to the problem instantly. But it is not enough to bring the earphones with you; you must learn to actually listen to them! It's surprising what the unwary videomaker fails to hear during the excitement of the shoot.

Which brings us to the outdoor videomakers biggest nightmare: ambient sound.

Ambience
Ambient sound (noise that occurs naturally in an environment) is everywhere. Ambient sound is on the loudest sports playing fields and in the quietest rooms, and it's one of the audio technician's worst enemies. While ambient sound supplies the ear with valuable information about a locale, it can overwhelm the desired sound if not controlled.

Some ambient sound is controllable. You can turn off air conditioners and move vehicles. If you can't shut off a very loud sound source, there is usually little you can do about it short of relocating your shoot. This is what most people do if the source of the ambience can't (or won't) move.

Sometimes you will overlook ambience until it's too late. Once you set a good level for your talent in the earphones, the purr of an airplane passing overhead may not be easily detectable. But you will surely hear it on playback, so you must learn to listen for it on the shoot.

The supercardioid and unidirectional mikes already mentioned help you fight ambient sound due to their cancellation effect. Careful miking and level setting will help, too. It's important to note that some ambient sound helps your recording by maintaining a natural audio continuity. You don't want your talent to speak in an atmosphere of complete silence unless the situation calls for it. For example: if a couple were chatting beside a creek, you would expect to hear the sound of flowing water, and perhaps birds chirping in the trees. It's your ability to control the volume of these sounds that is important.

Cloudy Skies
Rainwater and audio gear don't mix well. Permanent damage can result from even the smallest amount of water, especially to the more delicate condenser mikes. Rain or shine, bring along a good case for your gear. Call the weather station to see what the weather will be like during your shoot. And even if the forecast is fair, don't forget that it's never more likely to rain that when you decide it's time to fix your roof, wash your car or shoot some video. It never fails!

Sometimes your script or event will call for you to shoot in the rain. In such situations, your best bet is to make sure the rain stays off of every piece of equipment. Plastic camcorder weather covers work well and have few negative effects on the camcorder's operation. But any kind of cover on a mike does effect its operation by cutting out sounds and muffling the resulting audio. Instead of wrapping their mikes in plastic, Hollywood sound engineers place a bent plastic "roof" on booms to keep direct rainfall off the mikes. Placing a good mike directly in the rain is a poor gamble at best.

Finally, rain makes a lot of ambient sound, and when shooting outdoors it's nearly impossible to get away from. It will beat noisily on anything you place above your microphone or camcorder. If you can do so without trouble, change your script to shoot in dry weather.

Fade Out
Outdoor audio may sometimes be difficult to record, but clean audio is always worth the effort. Armed with the right knowledge and the right equipment, you can overcome most problems discussed in this article.

Just don't forget those extra batteries!