Sound Advice: Choosing Microphones and Where to Put Them
Alternatively, I could call this article “The Microphone Wars.” Everyone in the audio business has a favorite microphone, and the debate rages on. Since I brought it up, I will put forward my example of a great microphone: the vintage Neumann U-87 that I purchased (used) in 1983 in a vast used-equipment warehouse in New York City, now long gone. The U-87 is great for studio work such as voiceovers, and one of the finest sounding microphones of all time (in my humble opinion). Others will disagree, because that’s the nature of the microphone wars.
In any case, choosing high quality microphones for your on-location recording is a good thing, but the real trick in capturing sound is proper microphone placement. You can get much better sound with a poor microphone put in the right place, than you can with a good microphone put in the wrong place. In general terms, depending on the type and quality of the mic, you want it somewhere between 4 and 30 inches away from the sound source—the actor’s mouth in the case of dialog. A simple hand-held mic, for example, will need to be about 4-6 inches away. A high quality shotgun might be up to 30 inches away. The person operating the mic boom (a long pole that holds the mic) will have much to do with this. The sonic environment matters too, so, as with everything in audio, it depends. Leave enough time in your schedule to experiment, and listen to the results. Use your ears.
Quite a few video producers and directors insist on only using a lavalier (the tiny microphone that clips to the shirt or tie), but this is borne of convenience and ignorance. If you have a professional sound person working with you, they will likely go with a shotgun on a boom pole. This is because shotguns are usually higher quality microphones, and when placed on a boom can be maneuvered into a better position for sound capture. Lavaliers (lavs) can be fine, but they are prone to picking up rustling sounds from clothing, and they are not very effective when the actor turns their head. Lavs are wonderful when you need them, but pros usually start with a shotgun mic on a boom. Good boom technique, by the way, is acquired with experience. A quality shotgun on a boom is the best way to get professional sound, but do not enter into it lightly.
Since many of you will be working alone or without a sound person, defaulting to a lavalier is often easier because it can be clipped on the talent and doesn’t need someone to handle the boom. And you know what? That’s OK! Lavs are designed to pick up voices, so if you are using a good one and put it where it needs to be (usually in the middle of the chest), it’ll work fine. You can also hide it under a tie or inside of a light shirt, but try not to let the clothing touch it or you’ll get some nasty rustling. Gaffer tape (don’t use duct tape) will be your friend when arranging a microphone under a tie. Make a slight bulge around the mic to protect it from rustle. One other reason you might choose a lav over a shotgun is that some subjects become very shy when you put a microphone in their field of vision. A lav is essentially invisible, and I have chosen to use one simply to get a more relaxed, and thus better, interview.
Lavaliers can also be used with a wireless kit. It is plugged into a transmitter, which sends the signal to a receiver, which is plugged into the camera or into a mixer and on to an audio recorder. Wireless kits can really save you when there is no other way to get what you need, but they also introduce more issues, such as more gear wrangling and the real possibility of interference from cell phones and stray frequencies.
A lavalier is not appropriate, however, for gathering sound other than dialog. There are better microphone choices. (Sidebar: I once used a lavalier under a washtub bass when I recorded a jugband, and it worked beautifully). For environmental sounds, use a stereo microphone, or for specific sound effects, use a hand-held or the shotgun. As always, it depends on what gear you have and the circumstances you find yourself in. Capturing good sound requires flexibility, innovation, and expertise, but you can do it. Put the right mic in the right spot, and listen.
Remember that capturing audio is never a “set it and forget it” thing. You always need to pay full attention to the recording. A clothing rustle can ruin a take, or a plane will fly over, or someone will cough, so listen (monitor) closely on headphones, or assign someone that task. You can monitor from the camera directly (it usually has a headphone output), or better, a mixer if you are using one. There are plenty of issues with correct monitoring, too, but the most important thing is that you listen at a level that gives you the information you need. Turn it up until you feel as if you are inside your own sonic universe. If you find yourself in a situation where listening on headphones while shooting is not possible, then at the very least (this is not a recommended practice) record the first couple of takes, rewind, and listen closely to what you got before continuing. It’s a scary way to proceed, but making movies is often scary. Ya do what ya gotta do.
The very popular DSLR’s (Digital Single Lens Reflex Cameras) bring new problems. Many of them have no audio input or headphone output at all, so you will need to record “dual system,” meaning video to the DSLR and audio to a separate recorder. Many would say it’s the best way to go in any case, but it will probably necessitate having an audio person on set. This is a good thing, as you can’t wrangle the camera, lights, talent, and a full audio kit on your own.
For professional monitoring, use a closed-ear type headphone. This means it wraps around the entire ear and blocks out the noise of your surroundings. Earbuds or crappy headphones will fool you into thinking you got something you did not, and that’s actually worse than knowing you did not get what you want. Say that three times fast.
The takeaway of all this is that (without knowing your circumstances), you should probably plan on using a shotgun on a boom. Can’t do that? Use a lav. Can’t do that either? Use a wireless kit with a lavalier. Still stuck? Hide a microphone as close to the talent as possible. No good? Then I’ll say here what no sound person will ever say to a director on set: take the time to rethink how you are getting the shot, and revise the plan to better accommodate audio.
To do this right is a complex process that requires a working knowledge of microphones and myriad other types of audio gear, boom operation, good listening skills, focus, and the expertise to evaluate circumstances, but the above notes will, at least, start you thinking about how to capture good sound for your project. That is not a small thing. Giving consideration to the sound is exactly what you want to do. If this is all just way too complicated, and you are ready to run around the room screaming, followed immediately by eating way too much chocolate ice-cream, then consider yourself the ideal candidate to hire a professional sound person. But, in any case, share the ice-cream.