Good videomakers know how to divide their undivided attention to videomaker whenever location sound enters the picture.
Try this experiment: Turn on your TV, button the volume all the way down. Watch for 15 minutes, switching channels to try out a variety of programs. Get a sense of how well you can understand what’s going on just from the pictures.
Next, turn the volume up and turn the brightness all the way down so you can hear the sound but can’t see the picture. After 15 minutes, you’ll probably agree that the basic story-line content of most programs is conveyed more through sound than picture.
Despite its importance, audio is the most neglected aspect of hobbyist videomaking-and nowhere is the problem more acute than when you’re shooting on location.
In a living room “studio” you can reasonably expect quiet, and you can take control of many potential noise sources such as refrigerators and air conditioners by shutting them off. When you’re on location, outdoors or in, you’re often faced with much noisier circumstances-with less control over them.
Understanding some of the basic principles of recording sound in the field is as essential as understanding how to frame your shots. Sound recording is a very major part of professional film and video production, where elaborate 64-track sound mixing is not uncommon.
In a big-budget Hollywood film, there can easily be a half dozen different sound tracks-just to recreate the back ground sounds of the beach: two tracks of the ocean, one of the wind, one of birds flying by and two of families talking in the background.
While amateur and semi-pro video sound tracks are not nearly as complex, aspiring moguls with tin-pan budgets do require considerable ingenuity to make do with simple one- and-two track audio-for-video production.
Scout It Out
If you’re feeling more than casual about a location shoot (i.e., getting paid for it) it’s best to scout it out at least a day or two in advance so you have time to borrow or buy any special audio cables, adaptors, or other accessories you may need.
If you get really serious, you should put together a kit with every conceivable audio adaptor and cable you may ever need. Add two or three types of external microphones and you’ll avoid many of the most frequent headaches.
The ideal spot to locate your camera is usually not the ideal spot to pick up sound. If you’re shooting people speaking or performing, you almost always want to be at least S or 10 feet back- often further back if you need to cover an entire stage.
The best audio pickup is usually obtained by placing a microphone within a few feet of the sound source. Except when you’re shooting extremely close to a person speaking, this means you’ll usually get best results with an external microphone-not the microphone built into the camera. Or, you can “go direct.”
Picking up sound properly requires experimentation, patience, and practice. A fancy microphone in the wrong hands will not sound nearly as good as an inexpensive mike in the hands of a professional boom operator who has spent years learning to point the mike in just the right direction while getting it as close to the source as possible without entering the frame.
The universal rule for locating your microphone is to get it as close to the sound source as possible. The closer to the source, the higher the ratio between the desired signal and the unwanted noise (street sounds, air conditioners, refrigerators, office clatter, etc.) which inevitably accompanies every location-sound recording.
When recording a person talking, it’s usually best to point the microphone not toward the mouth, but toward the lower neck and upper-chest region. This lets the natural resonance of the upper chest cavity deliver a fuller, mellower sound quality, and also helps avoid annoying “pops” from percussive consonants like P’s and B’s.
You should always carry a roll of gaffer’s tape with you to neatly tape down long microphone cables. Be especially careful at spots where people may trip over the cords.
Avoid running mike cables alongside electrical wires, because more hum is induced as these wires get closer. If the mike cables must cross an AC power cable, it’s best to cross at a 90-degree angle to minimize hum.
The only exception to the “get the microphone as close to the source as possible” rule applies to very loud sounds which cause distortion when you get too close. This problem occurs more frequently with condenser microphones, because it’s more difficult to overload dynamic types.
For this reason, many condenser microphones include built-in “attenuator pads” which can be switched in to reduce the distortion level by 10 or 20 decibels.
When such attenuators are available, it’s always preferable to get the mike up close and attenuate it, rather than keep it further back without attenuation. The only way you can detect distortion is by listening to the signal as you record it.
Headphone Have It
You’d never think of shooting pictures with your video camera without looking through the viewfinder would you? Yet, when it comes to sound, the number of people who make no attempt to monitor their audio signals is astounding.
When you’re fooling around with your camcorder among family and friends you can afford to be sloppy, and risk a “bad take.” But when you’re shooting “professionally”-for money, or for something that really matters to you-you should always wear headphones.
The only exception to this rule applies when you’re shooting silent footage-cutaway shots, for example, which you intend to edit into scenes already having a sound track.
It you’re using open-air type headphones, which let a lot of ambient sound get mixed in with the signal, be sure you’re hearing the desired audio through the headphones and not just through the air.
At loud concerts, for example, the sound sources can be difficult to distinguish and you may need an additional headphone amplifier to boost the signal loud enough to rise above the din.
The Final Mix
Depending on the sophistication of your production, you may wish to record a minute or two of background “room ambience” whenever shooting on location.
This ambience track, also known as a “room tone,” comes in handy when you’re editing and need blank audio to maintain continuity with the rest of the material you’ve recorded. Your post-production audio setup may also include a small mixer and an equalizer to change the tonal characteristics of your field recordings.
As you gain experience editing the sound, you’ll also gain skill recording in the field, since we learn from our mistakes. No matter what, remember to wear those headphones-you’ll learn even quicker!
Something Sound Funny?
Wearing headphones is as essential to video production as looking through the viewfinder. Following are typical sound problems you should be listening for.
HUM:This is probably the most common audio bugaboo, sounding like a very low-pitched tone mixed in with the signal.
Hum can come from many sources. Proximity of a microphone or your camcorder’s body to electrical equipment such as TVs, motors, and fluorescent lights is a common low-grade culprit. Hum can be magnetically “induced” just by placing a mike cable next to electrical power cables, even though there is no connection between the wires.
The most catastrophic-sounding hum is usually attributable to “open grounds” in which the metal shielding of the audio cable becomes disconnected from one end of the audio line. This is usually the culprit if you get hum when you touch a microphone or other piece of equipment.
You can cure “open ground” problems by attaching a wire from the metal chassis of the VCR or camcorder to the metal case of the microphone, console, or whatever else you’re using. Try to find a metal screw which you can loosen slightly from the chassis to make this connection.
WIND NOISE: This doesn’t sound like the howling wind you hear in
horror movies. If it did, there’d be little problem!
Wind sounds like a constant popping or sense of banging because the shifting air pressure overloads the microphone’s diaphragm, thrashing it from one extreme to another, You almost never hear this noise with your own ears, because it’s created within the microphone itself. You must wear headphones to spot it.
You can help reduce wind noise by putting a foam “wind screen” over the microphone to absorb some of the wind’s energy, and by placing the microphone behind a wind shield such as a piece of cardboard.
- DISTORTION: Most people already know what distortion sounds like, but it can be difficult to describe in words. At its worst, a loud buzzing sound accompanies the signal.
Try listening to a portable cassette player or radio when the batteries are almost dead, with the volume cranked up all the way, and you’ll have a good taste of what distortion sounds like.
If you detect that the distortion is originating from a microphone, move the mike farther from the sound source. If the mike is a condenser type, use its attenuator to cut the signal down.
If distortion occurs with a direct-feed setup, you can lower the signal level by either reducing output level, reducing input level, or by using an attenuating patch cord between the sound source and your VCR.
- WEAK SIGNAL: Surprisingly, it’s sometimes difficult to notice a weak signal when listening with headphones, because you also hear the sound directly through the air. It can be difficult to discern how much you’re hearing through the headphones.
The best way to check for strong enough levels is to make a short test recording and play it back through the headphones. If the main sound seems garbled, or you hear a lot of background noise mixed in with the signal, then you should get closer to the sound source.
Cliff Roth, a freelance writer and producer, teaches audio production at the Institute of Audio Research in New York, and has taught video production at schools in New York and for Falcon Cable TV in Los Angeles. He is currently working on an independent film, “Subliminal Supermarket.”