Why? Simple- most audiences will forgive a few bad shots, but they won’t tolerate bad sound. It’s just too annoying and difficult to sit through and still follow the story onscreen.
Fixing audio problems after the fact is often a painful, tedious, and time-consuming process . Not only that, but some audio problems are simply unfixable in post-production. You just don’t have the same flexibility that you have with picture.
So that’s why I say, if you have bad audio, you have a bad project. But don’t despair. I’m gonna break down some of the most common audio problems in filmmaking and go over methods to avoid them altogether and give you some simple suggestions for how to fix them in post-production.
WIND NOISE
Symptom:
Frequent rumbly loud noise caused by excessive wind hitting microphone.
Preventing It:• Block the wind by using a zeppelin, windjammer, windfoam, or moving behind any large structure.
• Activate “low-cut filters” commonly found on microphones and mixers to diminish the low frequency end of the signal which is typically the sweet spot for wind noise.
Fixing It:
• Using an equalizer you can also decrease the low frequency end of the signal to diminish rumble caused by wind noise. Graphic equalizers are typically found on mixing boards, as stand alone rack units, or more recently, as part of audio and editing software programs.
BACKGROUND NOISE
Symptom:
• Consistent and distracting hisses, hums, noisy crowds or other undesirable noise on location that make it harder to hear the main dialogue. Most commonly occurs in large events and other locations where you have little control over the environment.
Preventing It:• Use a shotgun mic that focuses on sound only in the direction it is pointed at and diminishes the level of sounds coming from the sides or back of the mic.
Fixing It:
• Using an equalizer to adjust the high end of the audio signal may decrease some sounds, such as high frequency hisses caused by air conditioners and other machinery or traffic.
• Similarly, using an equalizer you can also boost the prominence of dialogue by increasing the middle frequencies, which cover most people’s voices.
ECHO
Symptom:
• Sound reverberates and bounces off of hard surfaces causing sounds to repeat. This is most common in rooms with little or no furniture.
Preventing It:• Shoot only in rooms that have carpet, drapes, or soft furniture to greatly decrease the effects of echo.
• Hang some sound blankets or lay down a large area rug to absorb some of the sound bouncing off the walls and floor.
Fixing It:
Record it right the first time, because echo cannot be fixed in post-production.
INCONSISTENT LEVELS
Symptom:
• Sound levels at times are a little too soft or too loud and don’t match earlier dialogue recorded in the same scene. Typically, caused by subjects moving closer or farther from mic, poor booming, or using different types of microphones within the same scene.
Preventing It:
• Pay more careful attention to mic placement when booming.
• Use a mixer to more accurately set levels for each subject and mic.
• Mic subjects with a lavaliere mic so subject-mic distance stays consistent.
Fixing It:• Use audio software such as The Levelator or Sound Soap to make all levels more consistent across the board.
• You can also (more painstakingly) monitor and adjust the levels of your entire audio track manually during editing.
OVER-MODULATION
Symptom:
• Loud, rumbly, unintelligible audio caused by sound levels that were too high during recording.
Preventing It:• Wear headphones and carefully monitor audio levels
• Move the mic a little farther away from your subject to avoid over-modulation.
• Many cameras and mixers also have a limiter function that you can activate to keep sounds that are too loud from over-modulating into complete distortion. However, beware, all limiters are not created equal. Test beforehand to ensure that your device’s limiter function doesn’t completely clip or cut-off loud sounds.
Fixing It:
There’s really not much of anything you can do to actually fix audio that was originally recorded over-modulated. There are however, some common work-arounds- almost all of which are time-consuming creative compromises…
• Salvage the segment by recording a voiceover in place of the original dialogue or by replacing the audio track with music to make it musical montage.
• Have your performers do an ADR (Additional Dialogue Recording) session to redo the dialogue. This is undesirable for most documentaries and still a major hassle with actors because they must match the exact movement of their lips and the tone of conversation, not to mention that you still have to recreate the ambiance of the original location for it to work. (*photo courtesy of Columbia-Academy.com)
FINAL CONCLUSION
Like so many other things in filmmaking (and life), an ounce of prevention is worth a pound of cure. You are always better off doing everything you can to avoid these nagging problems than spending your precious time and energy in the edit room trying to fix them.
Remember, you can’t have a good project without good sound. And good sound always separates the amateurs from the pros and the festival winners from the festival selections. Happy guerrilla filmmaking!
Til next time, I wish you all peace, love and video.
-Ant.
(*This article was originally published in the September 2007 issue of Student Filmmakers magazine)
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