Sound Advice: Interview Audio

From network magazine shows to documentaries, from the local news to Junkyard Wars, many video forms use interviews to either tell a story or reinforce a topic. In video production, we often spend our precious setup time getting the lighting and camera angles just right. This leaves little or no time to optimize the audio setup, and the prevailing attitude seems to be "just pin a mike on them and it’ll be fine." As our cameras and shooting techniques improve, our production audio quality should rise as well. With a little preparation and some attention to detail, your interview audio will rival the networks.

Start at the Top

Before shooting your next interview, do some research by watching similar interviews on television. There are plenty of choices, but the network news magazine shows (e.g. 60 Minutes or 20/20) are a good place to start. This type of programming offers excellent examples of interviews in various locations, under a wide variety of shooting circumstances. Look closely for what type of microphones they used, how many and where they are located. Listen closely to the sound for any lingering problems with room acoustics or background noise. How many people have microphones? Is the subject the only one with a microphone, or is the interviewer miked as well? Documentaries are another great place to look for interview audio techniques. Your public library likely has several to choose from – the Ken Burns documentaries for PBS are exceptional. If you can’t find anything at the library, try a local video rental store. The reason I suggest this is simple – somebody paid people to produce these interviews. If they’re doing it for a living, and on a national level, odds are they know what they’re doing. Of course, you can’t become an interview audio expert by watching a couple of TV shows, but you can get a good idea of how they work and what you’ll be expected to provide during your shoot.

Location, Location, Location

After you’ve done your research, it’s time to think about your upcoming interview shoot. Will you shoot indoors or outdoors? Is this a public space or will you have some privacy? Will this be a highly produced piece or more like a news shoot? Will the subject be seated, standing or perhaps even walking? The answers to these questions help define what you need to do to achieve the best possible audio.

Everyone expects an outdoor shoot to contain some background noise and there are only a couple of things you can do to minimize this audio problem. The first technique is simple – reposition to use your subject’s body as a shield between the microphone and the noise. Although this isn’t possible on every shoot, the human body can block quite a bit of sound when using a handheld or lapel microphone. The second technique is to use a highly directional shotgun microphone and position it so the axis of the microphone is perpendicular to the unwanted noise. Shotguns pick up almost no sound on their sides, so this is a powerful method for reducing background noise.

Indoor shoots provide their own challenges. In addition to potential noise sources like air conditioners and people in adjoining rooms, you also have to deal with room acoustics. Professional production companies often bring in sound absorbing blankets and other materials to minimize the effects of room echo and reverberation. The crew suspends the blankets on collapsible poles outside the frame of the video. It’s unlikely that you have the time or budget to provide this level of control. You’re better off shooting in a room that already sounds good, but it is possible to make a bad room better if necessary. Alternatively, you can embrace the sound of the room and keep it – even exploit it – as a character in the interview. I’m thinking specifically of large, ambient spaces like gymnasiums, malls and church auditoriums. If the space suits the subject, by all means use it to your advantage.

Choose your Weapon

Microphone choice will make a big difference in your interviews too. Sadly, there isn’t one perfect choice for all situations. There are three major categories of microphones for interviews and each has its strengths in certain situations.

The simplest choice for interviews is the handheld mike. Although a bit clumsy to manage, this method takes no setup time and will work wired or wireless. Use a handheld microphone when you’re doing quick man-on-the-street type interviews or any situation where looks are less important than speed.

If you have a bit more time to set up, the lapel microphone is an excellent choice for interviews. There are challenges for where to put the mike and how to hide the wires, but the sound quality will be consistent from take to take. Nice sounding lapel microphones are available at local electronics stores for as little as $25. You’ll need a few adapters to attach the mike to your camera, but this is an investment that will pay for itself many times over if you shoot interviews on a regular basis. Don’t forget to buy a foam windscreen for your lapel mike to minimize wind noise when outdoors.

The last line of defense for interview audio is the shotgun microphone. This option is a bit more awkward than the others, but it’s also the most professional. Many people shy away from shotguns because they require a second person to hold and position them. During a seated interview, you can use a microphone stand, but you might need a boom pole in other situations. Get the mike as close as possible, but remember to keep it out of the video frame at all times. Shotguns can be wired or wireless just like your other microphone choices, although it’s more common to see a shotgun wired directly to the recorder.

Fix it in Post

Once you’ve shot the interview, it’s time to edit. Today’s video editing software offers capabilities that were impossible just a few years back. A little extra time and care in this area will give your soundtrack a professional sheen. After you capture the interview footage and get the basic arrangement on your timeline, take a few minutes to work on the audio. The first step is to normalize each audio clip (Premiere calls this "Smart Gain, Vegas calls it "Normalize"). This process ensures that each clip reaches the maximum possible loudness without clipping. Next, add a highpass filter to each clip, set to cut off any sound below 100Hz or so. This will minimize any background rumbles and can eliminate the effects of wind noise. One nice feature of sweetening interview audio is that individual speaking voices have a very narrow frequency range, so the use of equalization can be very effective.

Professional shooters often record the interview audio on one channel and ambient or natural sound on the other channel. This allows the editor to blend in (or not) some of the character of the interview environment. You can do the same thing. Depending on your video software, you have the option of using only the left channel, only the right channel, or a blend of the two. Another version of this technique is to deliberately record a few minutes of ambient sound only, either before or after the interview. This gives you a sound bed to fade in and out of the interview audio as needed. You can use it to make a consistent audio backdrop or to patch uneven edits between clips.

These are just a few tips and hints for better interview audio. Get out there and shoot some interviews. Experiment with the various microphone choices and compare the results back at your editing computer. After some time and experience, you’ll instinctively know which microphones and techniques work best in different situations. In no time, your interviews will sound as good as the networks.

[Sidebar: Just Get Over It]
Sometimes, you can’t eliminate distracting noises in your interviews. I once shot a video at a private swimming pool in a housing development. We were far away from the noise of the city and the trees offered further isolation from errant sounds – except for this one bird. It had the lungs of an eagle and the shrillness of a seagull. Best I could tell, this bird was easily 100 yards from our location, but it made its way onto the soundtrack of virtually every frame of video I shot that day. There was absolutely nothing I could do about it, so I labeled the bird "audio color" and decided to live with it.

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