Twelve ways to improve your audio after you shoot.
"Audio post production" is a fancy-sounding term that basically means "anything you do to your audio after you shoot." Even that definition leaves many folks scratching their heads, so I m going to take this column to explore twelve specific things you can do to fix and enhance your audio after the fact. For those of you feverishly guarding your checkbooks right now, rest assured that you can accomplish everything on this list with affordable consumer equipment.
This list is designed more to illuminate the possibilities and spark your imagination than to teach techniques. With that, here goes.
In audio post production you can:
- Match Levels
In a world crowded with extremely loud sounds, quiet voices and everything in between, getting a consistent signal level on tape can be a real challenge. An interviewer may be dramatically louder than the interviewee, or alternating lines of dialog may end up at noticeably different levels.
In audio post production, you can level out even the most uneven soundtrack. By listening to your audio and manually controlling the volume as you edit, you can bring up the level of quiet sounds and reduce the level of loud ones. "Riding the levels" may take some practice, but the end result is a soundtrack that’s much easier to listen to, a soundtrack free of very loud surprises.
To manually control audio levels, you need an audio mixer or record deck with manual record-level controls.
- Control Dynamics
If you’ve ever tried to manually control record levels (see previous section), you know how challenging it can be to catch fast changes in volume. A compressor may be the solution. It’s like a box containing a tiny soundperson with very good reflexes. A compressor will reduce the level of loud sounds and lift the level of quiet ones. Best of all, it responds in just a fraction of a second.
Because it’s so fast, a compressor will do more than just match one sound to another. It will actually level out individual words and syllables in a sentence to give the voice a much more urgent, up-front quality. Television advertisers use compression all the time, to make their ads seem to "jump out" of the speakers. With a compressor, your audio can do the same.
- Add Audio Effects
By running your soundtrack through a digital effects processor, you can doctor your audio in ways you ve never dreamed of. Want your stranded victim to sound like she’s yelling from the bottom of the Grand Canyon? No problem–an effects processor can add convincing echoes to the sound. Need to turn one singing kid into an eerie, ethereal children’s choir? Check out a chorus or "detune" effect from an audio effects processor. A flange effect is equally chilling, making the human voice sound distinctly robotic.
Audio effects needn t be so dramatic. To make a dubbed basketball announcer sound like he’s actually in the gym, a touch of long reverb from an effects processor will do the trick. Any time you need to simulate an acoustic environment without actually being there, an effects processor can help.
- Add Music
If music is the universal language, adding some to your video will really help you speak to your viewers. Enhancing your video with music is easy, and can add a real professional touch to your production.
There’s no better way to paint a mood than with music, a fact that every Hollywood director knows well. Music allows you to conjure up such feelings as love, tranquillity, nostalgia, excitement, anticipation, even fear. Buyout music libraries allow you to use quality instrumental music without licensing hassles. Before you use a popular song in your video, though, make sure you understand copyright law (see "The Copyright Riddle" in the December, 1996 issue for more information).
To add music to your videos, you’ll need a CD player, cassette deck or turntable; some music; and a VCR with audio-dub capability.
- Add Sound Effects
What’s an explosion without a kidney-shaking rumble of sound, or a barroom fight without "whump," "smack" and "crash"? The answer is–yawn–not much!
Sound effects can add incredible drama and punch to a video, especially productions with a lot of action. Sound effects CDs are inexpensive and easy to come by (you can find them advertised in the pages of Videomaker), or you can make your own effects with simple household objects. Wherever you get them, a few key sound effects sprinkled through your video can be the difference between "Wow!" and "Is it over yet?"
To add sound effects to your videos, you’ll need a CD player, cassette deck or turntable; sound effects; and a VCR with audio-dub capability.
- Record Voiceover
In some types of productions, the off-camera voice is the glue that holds the whole video together. This "voiceover" can deliver instruction, illuminate something on-screen, fill in a subplot or comically harass the on-screen talent.
You don t need a golden voice or a professional script to do effective voiceover. All you need is a microphone and a good sense of where voiceover would be appropriate. This facet of post-production is one of the most common, and for good reason. It works!
To add voiceover, you’ll need a microphone and a VCR with audio-dub capability.
- Replace Dialog
Sometimes, for whatever reason, you may find that some of your on-screen dialog just doesn t sound right (or is completely inaudible). Don t feel bad; this happens to the pros all the time, too. Their solution is "automatic dialog replacement" (or ADR), a not-so-automatic means of re-recording dialog in sync with the picture.
You can do the same thing in post-production, provided you have the talent and the patience. You can use your on-screen talent to replace his or her own voice, or you can use an entirely different person. Or, for laughs, you can pull a gender-bender trick and replace a man’s voice with a woman’s.
To replace dialog, you’ll need a microphone and a VCR with audio-dub capability.
- Add Ambient Sound
Ambient sound is the wash of "random" noises that give a location its aural personality. Since our ears tell us as much about our location as our eyes, ambient sound is a great way to sell your viewers on what they re seeing.
Provided Rover doesn t give you away, the sound of a bustling restaurant will turn the corner of your living room into a four-star getaway. The roar of a cheering crowd will turn eight actors and one empty stadium into a Superbowl bash. Many CD sound effects companies offer ambience discs, or you can record your own with your camcorder.
To add ambient sound, you’ll need an audio recorder, ambient sound and an audio mixer.
- Apply Equalization
Equalization allows you to change the tonal balance of your sound by increasing or decreasing certain frequency ranges. With even the simplest equalizer, or EQ, you can make a thin voice sound bassy, or a muddy piano recital sound clear.
Equalizers with more control allow you to pinpoint and adjust specific frequencies. You can then reduce the rumble of wind noise, fatten-up a nasal-sounding microphone or add "edge" to a lifeless sound effect. For sound correction or enhancement, equalization is an indispensable tool.
To add equalization, you’ll need an audio mixer with a built-in equalizer, or stand-alone equalizer.
- Reduce Noise
Sometimes, unwanted noise plagues your sound. It may be hum from an air conditioner, hiss from a poorly set up audio mixer, or buzz from a bad cable. While there’s no miracle way to totally eliminate noise, there are ways to clean up your soundtrack.
Equalization is a good way to eliminate many noises, especially those at frequencies above and below the human voice. In addition to EQ, there are noise-reduction devices designed to automatically reduce hiss without affecting other sounds. More complex systems will take a "fingerprint" of the noise to find and eliminate it from your audio.
To reduce noise, you’ll need an equalizer and a single-ended noise-reduction processor.
- Change the Pitch of a Voice
Whether for comedic or dramatic effect, there’s something striking about altering the pitch of someone’s voice. Today, you can find affordable processors that will do this in very convincing fashion.
Taking a man’s voice down in pitch makes for a huge, ominous sound. Transposing any voice upwards makes for a funny chipmunk sound at the extreme, or a child’s voice at more subtle settings. Some processors alter the pitch separately from the formant (non-pitched sounds), which allows you to maintain the recognizable character of a voice even while changing its pitch.
To change voice pitch, you’ll need a pitch processor or harmonizer.
- Edit Sound With a Computer
This may be the most powerful post-production process of all: computer-based sound editing. For a relatively modest investment, you can set your home computer up to do amazing things with audio.
You can edit sentences together on a word-by-word basis, reverse sounds, change their tonal characteristics, layer sounds without limit, stretch and compress voiceovers without changing their pitch, add effects–you name it. There’s virtually no limit to what you can do to your audio once it’s in digital form.
To edit sound on your computer, you’ll need a sound card.
This list is just a sampling of the things you can do to your audio during editing. In today’s audio post-production world, if you can imagine it, you can do it.