Audio for Video
So, you've bought a shiny new digital video camera and you're blown away by the image quality. But what about the audio?
Audio is possibly the most overlooked element in video production. That's too bad because audio quality can make or break any video project, regardless of budget.
You may be able to fix some things in post-production, but why go to all the trouble when you can get it right the first time? This article explores 10 tips for gathering the best possible audio on your next shoot. Some are common sense tips, but many are hard-earned lessons from the field.
Plan Ahead
When shooting on location, a smart videographer scouts the site before the shoot, looking for ideal lighting and backgrounds to produce the best image possible. For your next shoot, scout with your ears too. Listen for traffic noises, machinery, animals and aircraft-anything that might ruin the audio during the shoot.
Depending on your topic, some background noise may be acceptable or even desirable. Just make sure you can hear your subject over the ruckus.
Use an External Microphone
Unless you have a high-end professional camera, your built-in microphone is absolutely worthless for anything more than your 3-year-old's birthday party. First, the microphone is built into the camera's body, and is very sensitive to noise from zoom, focus and tape drive motors. The second problem is a matter of distance. Even though you can zoom in on a subject from across the room, the microphone is stuck 20 feet away. Trust me, you need an external microphone.
Choose the Right Microphone for the Job
OK, I've convinced you to use an external mic, but what kind? There are four basic types: handheld, lapel, shotgun and boundary.
Handheld mics, typically used by news reporters, add a newsy feel to your video. Directional handheld mics minimize background noise while nondirectional mics collect the audio flavor of the scene.
News anchors and sit-down interview participants often use lapel, or lavaliere microphones. They are useful anytime you want to get close to the source, but minimize visual impact.
Shotgun microphones, highly directional and often used on TV shows and movie sets, usually suspend from a boom or "fishpole." Shotgun mics typically hover just out of the video frame and point directly at the subject.
If you shoot legal or corporate video, the boundary microphone could be your new best friend. Boundary mics turn an entire table, wall or floor into a pickup surface. Unfortunately, their incredible sensitivity is a double-edged sword. They clearly pick up voices from every direction but also amplify shuffling papers and air conditioner noise equally.
Different Kinds of Mics
A. Boundary Mic-Also PZM, lies flat on a table or surface and is typically used for miking people sitting around a table.
B. Shotgun Mic-Usually has a highly focused pickup pattern and is best at gathering sound at a distance or in a noisy environment.
C. Lapel Mic-Is very small and can be hidden on or around the subject to completely conceal its presence.
D. Handheld Mic-Comfortable to hold in the hand, it is commonly used by television newscasters, singers, public speakers and talk-show hosts. It's ideal when you want the talent to directly address the camera.
Use a Windscreen
You're familiar with the effect of wind blowing into a microphone. The resulting rumble masks all but the loudest sounds, making the audio useless. Subjects speaking close to a microphone also produce small blasts of wind from their mouths. One of three basic windscreens will minimize or eliminate these problems altogether.
Foam windscreens are the most common since they are inexpensive, and work great for both handheld and lapel microphones. Although shotgun mics also use foam windscreens, the pros usually use a special type called a zeppelin. This special-purpose windscreen gets its name from its shape. It looks like a long, skinny blimp. Porous cloth or fur typically covers the mic and blocks the wind, while letting sound through unharmed. A shotgun microphone mounts inside the zeppelin where the entire mic is protected from audio-wrecking wind noises.
When you record the narration for your next video, consider using a hoop-style windscreen to improve the sound quality. Hoop screens are usually about six inches in diameter and covered with one or two layers of fine mesh cloth. Recording studios worldwide use this type of windscreen on critical vocals, and you can too.
Position Microphones Properly
Some simple attention to microphone placement can make a dramatic improvement in sound quality. Take the shotgun mic, for example. Its extreme directional characteristics and high sensitivity make it great for picking up audio from a distance. But point a shotgun up at your subject from the ground (instead of overhead), and you might pick up birds singing in the trees or the 3:30 flight to Albuquerque.
Misuse of lapel microphones is just as easy. Ideally, they are worn on the outside of clothing, attached to a lapel, tie or shirt. However, hiding lapel mics under clothes minimizes wind noise and visual distractions. This location guarantees a muffled sound and the sound of cloth rubbing on the microphone. If wind is the problem, try positioning your subjects with their backs to the wind. If cosmetics are the issue, try a smaller microphone, a less distracting location or a shotgun mic.
Learn to Deal with AGC
Automatic gain control, or AGC, is built into many cameras on the market. This seemingly magic circuit constantly monitors your incoming audio, then keeps the loud sounds from getting too loud and the soft sounds from getting too soft. Sounds like a great idea, doesn't it? It's not a bad idea, but problems crop up later during editing when you try to match clips from different takes. One take will be loud and strong, but another will be softer with more background noise. Now what are you going to do?
There are a couple of solutions. First, have your talent re-take the material, starting before the break point. This will get the AGC working in a similar range to
the previous take, making your edit point more consistent. The second method is to turn the AGC off. This only works on certain camcorders, but if yours has this feature, use it. You can adjust the audio level manually for consistent sound, take after take.
Monitor with Headphones
If your camera has a headphone jack, buy a pair of good headphones and keep them in your camera case. The next time you shoot, you will hear exactly what the microphone hears, making mic positioning easier. You will also catch bad connections, dead batteries and background noise before you commit it to tape. This is an absolute must and will save you much frustration and embarrassment.
Get Connected
Audio cables and adapters are a necessity for the videographer-just make sure you have the right ones before you shoot (see Figure 37-5). Wireless mics often need jumper wires to connect the receiver to the camera. Professional microphones use three-pin XLR connectors that won't plug into most consumer and prosumer cameras. For these mics string together several adapters or buy an interface box. If you're connecting to a sound system or other audio equipment, bring every adapter you own to the shoot. You'll need them.
Get In Close
Regardless of your microphone choice, the closer you get it to the subject, the cleaner your audio will sound. Position the handheld or lapel mic a little closer than you previously had. Boom in as close as possible with the shotgun. This technique also reduces background noise and further improves your audio.
Bring Spares
Spare cables, spare adapters, spare microphones and spare batteries. This tip will save your skin in an emergency and give you some creative freedom. Perhaps you get to the shoot and discover your single lapel microphone won't work because there are two subjects speaking. Your spare shotgun or handheld microphone will work even better and you'll look like a very smart cookie.
Take these ideas to heart and your next video production can sound match the sound of a professional studio.