How to Record Better Sound

What do the movie The Making of Mr. Right, the television show Live at the Apollo, and American Express commercials have in common with your video productions? Sure, the former all had the advantage of big bucks pro gear and mega-salaried talent. But they also share the application of audio recording techniques that you can duplicate with consumer equipment. Like any enthusiast, we appreciate how simplicity can open up the creative floodgates. To get the best sound from your camcorder, listen up as I explain how to use pro techniques with consumer tools.

Proximity Matters
The sound recording tracks produced by modern camcorders are of pretty decent quality, in general. The number one problem with their sound is that the microphone, even on the best camera, is physically too far away from the subject that is being recorded. (As you may have noticed, it's mounted on the camera.) Additionally, the on-camera mike is set up for general use and not optimized for a particular environment or subject. Thus the main problem is a proximity problem. All of the other sound in the environment at hand is picked up by proxy. Moving the camera closer to the subject will lessen the incidental noises and other sounds in the environment, but will rapidly limit the flexibility of your shot.

Take a look at a news crew and you'll have your most basic solution to better sound. Notice that even though they have the best field ENG (electronic news gathering) cameras, there is still either a sound man holding a separate microphone closer to the subject, or the reporter himself is holding a mike. Or, in some instances you'll notice very small lapel mikes on the subjects. So there you have the most basic answer to the proximity problem--position the mike as close to your subject as possible.

Since most of us don't have access to a professional audio crew and equipment, let's focus on the tools you can use now.

Choosing a Mike
Let's begin with external mikes and learn what we can from professional performance scenarios such as a news crew or the sound on a television or movie set. First of all, to begin the comparison you'll need an external microphone to record your sound. They're available through many audio and video outlets, consumer and professional alike.

When you look for a microphone, however, you'll find that there are many types available, which can lead to some confusion. To sort through it, first choose the general type you'll need, then choose the pickup pattern.

• Wires or no wires? A good wired mike has the best rejection of noise, such as radio frequency (RF) interference, but one usually prefers to not see the wires in the shot; so assess this against a good 2-channel (true diversity) wireless system. Although a single-channel wireless system is more affordable, a true diversity system offers the best quality.

• Stereo or Separate Microphones? Stereo microphones can be very good but two separate microphones give much more flexibility than a stereo microphone. And they can of course be set up as a stereo pair when required. Certainly you want a couple of good mikes but that doesn't mean that they have to be expensive. Look for microphones that have balanced connectors (XLR-style) and a good frequency response (as close to 20-20,000Hz as you can get).
  

Pickup Patterns
What follows is a simplified breakdown of the most basic microphone types and their functions (see Figure 1 for diagrams of pickup patterns).

• Omnidirectional--picks up all around, every direction. All of the off-point rubbish is picked up, so this type is not typically on a list of general-purpose mikes. It's sometimes used in a Super Studio when there may not be a problem with any off-axis sound. Its use is limited because point-of-source sound is still the main concern; more so in the studio than in uncontrolled environments.

• Cardioid--picks up sound in an arc in front of the mike. This type of mike is the generally the best bet because it has a good field of pickup but still allows you to aim it at the source.

• Super Cardioid--acts like a cardioid but has some additional ambient pickup to the rear.

• Figure Eight--acts like a two-axis cardioid. Useful mostly for special applications, so not a good general-use option.

• Shotgun--picks up directly in front of the mike in a thin straight line. A good choice if you have someone aiming it constantly at the source or if your subject is stationary. A camera-mounted shotgun can sometimes be ideal for an application where the videographer is only concerned about picking up sound directly in front of his or her field of view.
  

Microphone Placement
When it comes to mike placement, you'll gain more by listening than anything else, but some general direction is useful (see Figure 2). Put the mike as close to the subject as is practical and aim it directly at the subject. Keep it from contacting any vibrating surfaces. Keep the mike away from any serious electrical or radio-frequency noises. Place it so that wind noise doesn't affect it. If your camcorder allows you to adjust the gain (audio level), run it as hot as practical without overloading (distorting) the signal.

And now for some special professional cheat hints:

• Taping a mike to a piece of foam on a broomstick can make a pretty good low-budget boom.

• Hanging mikes from the ceiling above your subject(s), as long as the mikes are out of frame, can give a pretty good result in some applications. Just make certain they won't fall and bop somebody on the head.

• Miking from both sides just out of frame by placing two mikes on a flat surface perpendicular to your sound source (such as a shelf or window frame) can give a good result for miking a room. Be sure to lay the mike on a bed of foam or a soft towel to isolate it.

Professional cheat hint number two: if you can't afford an external mike, consider this method of making a quasi-shotgun out of your existing camcorder microphone. Completely surround the camera's mike with some square pieces of cardboard attached with tape. When designing your quasi-shotgun, think of it like a set of blinders for a horse or perhaps a chute into which the audio falls (see Figure 3). Be careful not to obstruct the vision of the camcorder's lens at its widest setting. Also, if the sound you get from this system is too brittle, you might want to consider affixing some tissue or cloth to the inside of the construction (called a "wave guide"). With a little careful construction--and modification after listening closely--you can have a system that will reject sound from all directions but straight ahead.

Environmental Considerations
Indoors, the most common problem is unfriendly, spurious reverberation--that boxy or boingy sound; when you listen back and say, "That's not what it sounded like at the time." Close miking alleviates much of this but if you need more help, then try to make the room "softer." Commercial moving blankets (or anything soft of that approximate density) hung out of camera frame is a very good application if necessary, but a ruddy pain, so go for mike placement first. Let me add that blankets, bedsheets, curtains, foam rubber, and many other found items work very well in a pinch.

The second most common problem is noise in general. Again, smart mike placement will get you the furthest the quickest, but after that common sense comes in (close windows, turn off the air conditioner, wait until the refrigerator stops cycling its compressor). Block off unwanted sound sources with any of the materials described previously. For unwanted footstep noise on a hard surface, a rug or blanket will suffice if you place it out of frame. You can also re-orient your subjects in the room if the shot allows it, changing the axis of the mike's general pickup area to exclude unwanted noises.

Outdoors, the worst problem is unwanted noise. Mike placement as always is the primary attack. Here a shotgun mike and its highly directional pickup pattern may be effective. Aside from that, re-orientation and axis adjustment, as noted above, is your next line of defense. Finding creative ways to block off unwanted noise can help somewhat. The use of a shotgun (not the microphone type) for birds is not recommended, though you will inevitably consider this option.

Sub-mixers and External Sound Recorders
To boost the number of mike inputs available while you shoot, consider a small microphone sub-mixer. For example, you could get a six-input stereo output mixer and use two mikes for overheads (in stereo) and then use lapel mikes for the subjects with yet another mike for, say, the audience. Then, mix them as you like and send the stereo outputs of the mixer into the camera. Note to check first (listen!) that you're recording the balance you want and make sure you're not overloading or distorting the sound.

Another piece of equipment often used for audio acquisition is a stand-alone sound recorder for recording wild sound. Wild sound is defined as audio recorded separately on location without any type of synchronization to the video. You can run a sound recorder of some sort (stereo or multi-track) along with your camera if you have the ability to edit sound and visuals later. You could even use a separate camcorder as a way to get its on-camera mike closer to the action than your main camera's microphone.

Wild sound has many uses--including the recording of ambient or environmental noise at a location--but if you plan to synchronize the wild sound with the picture at some point, you may have difficulties. One trick here is to imitate the clapboard you see used in motion pictures. They put the board in front of the lens of the camera while the camera and sound recorder have already started so that later in editing the loud clack in the audio can easily be aligned with the visual of the board physically slapping down. This way, if you have a system that supports time code or perhaps a nonlinear editing system, you can align the start of the sound and picture accurately and very quickly when they are later joined together.

If you do not want to carry around a clapboard, a finger snap in front of the lens may do. However, one of the major difficulties you may have with wild sound is called audio drift--the tendency of the wild sound to subtly and slowly go out of sync with the moving picture. The clapboard trick does not eliminate drift, but if you keep your recorded wild audio segments short, you can minimize its effect.

If you happen to have access to an audio recorder with time code, so much the better. In professional applications, sound recordists use time code, a technology developed by the Society of Motion Picture and Television Engineers (SMPTE) for keeping track of the audio and visual information on a frame-by-frame basis for perfect syncrhonization. Some relatively inexpensive DAT (Digital Audio Tape) recorders can work with time code, but for the most part, time-code-based audio recording is for those with access to very expensive recording equipment.

Compressers and Limiters
Just one final note here on audio compressors and limiters: these devices are used extensively in professional audio-for-video applications. There is no substitute for hands-on experience with these items.

First of all, compressors and limiters are closely related to one another. Both work with the dynamic range of an audio source--that is, its range of amplitude or gain, from the softest to the loudest levels. Limiting automatically keeps the volume under a pre-determined level. A compressor, too, acts like an automatic volume control on what ever you run through it, only it works on both the quiet and the loud parts of the signal, boosting them or shutting them down to keep all parts of the signal within a pre-determined range of amplitude.

What do compression and limiting do for your audio? They give it a cleaner, more "even" sound that won't distort or overload the playback mechanism, even if it's a tiny little speaker on a cheap TV. They also bring all of the audio levels into a workable range so that everything can be heard at nearly equal volumes.

Going Shopping
When acquiring an audio system, try it out in real scenarios, and be certain you can return it in a reasonable amount of trial time if it does not meet your performance criteria.

If you have a limited budget and you'd still like to upgrade your audio capabilities, focus on an external microphone and a pair of headphones. Get only what you need, and develop your skill like the Red Baron.