Capturing audio on a video production shoot requires special recording techniques. Audio for video engineer Scott Hirsch explores best practices including location scouting tips, reducing echo and reverb when recording sound on set or in the field, and the importance of a good signal to noise ratio.
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- [Voiceover] The production shoot is where the seed of your creation first sprouts and everything is downhill from there. We have to ensure we capture the best audio available from the source. If we fail our mission here, we'll spend the rest of our journey wishing we could go back and we'll spend tons of time and energy fixing bad audio we could've easily avoided to begin with. Here are some simple guidelines to ensure you capture the best audio possible and also how to avoid and overcome potential pitfalls along the way.
Now before I get into any gear or specific miking techniques, I wanna talk about a few principles that aren't always mentioned. As people who are engaged in visual storytelling, we tend to focus on the visual aspects when we choose our location, we set up our shot, we block our actors, etc. Sound often comes a distant second in our consideration, unless we learn the hard way. So don't make the mistake of overlooking sound in your setup, even for the first time.
Rule of thumb number one: location, location, location. Location is crucial. Obviously in a documentary shoot, you're sometimes at the mercy of your location. It chooses you, rather than you choosing it, but even then most film makers get at least one personal interview or talking head style interview with their principle subjects. So don't make the mistake of conducting that interview in a noisy environment or echoey room and the main reason for this is that, that interview, even if it doesn't make it visually into the film, is often used as a voiceover for other footage.
When your voiceover sounds bad, it really cheapens the authenticity of your film and it makes your whole production look and sound cheap. Imagine a beautiful shot on the plains of Africa and instead of the warm David Attenborough voice guiding us through, you have a reverby, noisy, harsh voiceover. Don't do that to your creation. If you're location scouting for a narrative feature, the world really is your oyster. You can take into account sound during your location scout and the rule of thumb here is as visually pleasing as a location might be, you have to take into account how it sounds.
This means your location shouldn't be in an airplane flight path, nearby a freeway, near any loud school yards, fire stations, and that kind of thing. Trust me as tempting as it might be, and you will be tempted to say, we'll just fix it in post. Don't do that to yourself. Look for another location. Rule of thumb number two: treat your space. Reverb and echo of a room is nearly impossible to remove from a recording, even with all of today's noise reduction technology.
In addition, echo and reverb add on to the natural tone of a voice with comb filtered, unflattering sound reflections that'll degrade the quality of good sound. Now this goes for any documentary interview setup as well as narrative shoots. In any shot, with the exception of a wide shot, you're probably showing less than a 30 degree slice of the whole location. So, this gives you a large area to put sound treatment in to cut down on echo and reverb. I'm talking about pillows, blankets, duvetyn sheets, and if you really wanna get it right, you can bring along a few three plus inch thick panels of rock wool or rigid fiberglass.
Those really cut down reflections. So go the extra mile to treat your room all around your actors and gear paying special attention to reflective surfaces and the results are really worth it. Rule of thumb number three: adhere to the simple rule of a good signal to noise ratio. If signal to noise ratio sounds like difficult audio tech talk, let me break it down. It's really simple. You want the signal, which is the good sound you wanna capture, to be much louder in relation to any other background sound, which includes distant traffic, reverb, echo, airplanes.
That's the noise part. Just because an actor's voice sounds loud enough over background noise to you in the headphones, this isn't enough because we'll be increasing the levels and we'll wanna work with material in our post production mix, we need to do everything we can to ensure the difference in level is as large as possible between the voice or the signal you want over any background noise. So how do we accomplish this? The first rule of thumb is to get the microphone as close as possible.
The boom mic should always be just outside the frame or underneath the frame or as close as you can get it. Something might be becoming obvious here, this rules out the mounted camera mic. Yes, death to the camera mic. By being mounted on the camera, that kind of mic is always going to be too far away, unless you're right in the actor's face with the camera and that's fine for on the street interviews, but it's still not ideal since you get camera handling noise into the microphone. Other ways to ensure a good signal to noise are to follow my rules one and two, good locations and tame any reverb or echo.
Finally, the last guideline to good audio during your production seems like a no brainer, but you'd be surprised how often this gets overlooked. Listen to the audio with headphones as you shoot. If you're the director, sometimes that responsibility falls to you. It might fall to a dedicated sound recordist if you have the budget for that. It might fall to the camera operator, a producer, or even an intern. The bottom line is that someone must be responsible for audio quality control by listening to a set of closed-back headphones.
Closed-back headphones are the type of headphones that block outside noise so the person can hear just what's in the mics. They don't have to be noise reduction headphones or noise cancelling headphones, but they should be closed in the back so you really can isolate the source. Now along with the responsibility of listening comes the responsibility to make the crew aware of any problems. If a scene happens and there was a plane flying over or a distant siren or one actor puts his fork down on a plate loudly when the other actor speaks, as the quality control person, you may be the only one to have heard it, but you must make everyone on the shoot aware and insist that the take is done again.
Remember, you're the only one listening to what will end up in the film and if the director insists that the bad take with the bad sound was the best take, it's your responsibility to have actors do wild lines of anything that might be obscured. A wild line is a clean line of dialogue that you can redo right after a scene. It's just an audio take, but you wanna use the same mics and then that line can hopefully be substituted later in post-production for the bad sounding line.
OK, now that we have a good theoretical understanding of some simple guidelines to capture good audio, we'll next get much more technical about the appropriate gear and some techniques to use that gear on a shoot.
- Capturing audio and following the proper workflow for optimum results
- Sound editing—improving and restoring audio in post-production
- Mixing and exporting audio or preparing it for handoff to a professional audio engineer
The second and third steps feature Adobe Audition CC, a powerful audio post-production program with a host of tools to clean up, sculpt, and finesse your sound design. The seamless workflow to and from Adobe Premiere Pro makes it a powerful audio toolset. However, author Scott Hirsch's techniques work equally well in other video and sound editing applications. Watch this course to learn practical techniques for getting better sound in all your productions.
- Choosing the right gear, including lavalier and boom mics
- Syncing offline devices
- Working with audio in the video editor
- Moving files to Audition
- Choosing sources
- Cleaning up and getting the most out of nonideal audio
- Reducing noise
- Adding sound effects
- Mixing and adjusting levels
- Exporting and managing final files