The two most common microphones used on boom poles are shotgun microphones and cardioid variants (known as hypercardioid, supercardioid and cardioid microphones). Space precludes us from taking a deep dive into all of the variants and their differences, but suffice it to say that shotgun microphones have the tightest, most focused pickup pattern. A side effect of this tight pickup pattern is that most shotgun-type microphones also pick up a small, narrow pattern to the rear of the microphone. If you think about, this rearward pickup pattern sometimes isn’t a big concern, but if you’re using a shotgun indoors, this rear-facing pickup can often pick up undesirable room reflections, reverb and echo, resulting in an overall hollow and unappealing sound characteristic on the recording. Shotgun microphones are usually the wrong choice for recording clean, clear audio in reverberant indoor spaces.Using a cardioid variant microphone results in a wider pickup pattern than a shotgun, but cardioids also have very little to no rear axis pickup, too. Cardioid-pattern microphones are typically at their best on interiors and especially in spaces with a lot of room reflections. Boom microphones like shotguns and cardioids are a bit like golf clubs; there are a whole bag of them because each club excels at specific purposes. Microphones are similar; there’s no such thing as the “best microphone,” but there are a lot of choices on the market, each offering superior performance and sound quality in specific situations.
Mounting And Positioning Your Boom Microphone
Before we get too deep into how to correctly position your boom microphone, we need to cover the rest of the support gear needed to utilize a boom microphone. Besides the shotgun/cardioid microphone itself, you need to acquire wind protection for your boom microphone. You may think, “I’m only going to shoot interviews in offices; I don’t need wind protection.” Wrong. Even inside, boom microphones are so sensitive, they can easily pick up wind noise from HVAC registers that are quite far away. I can also guarantee, you’ll have a moment when you want or need to shoot an exterior scene or interview, for which you’ll need good wind protection. There are typically devices like windscreens available, which is a foam and plastic tube that slips over the microphone. These windscreens typically are fine for mild breeze or HVAC air hitting a microphone when shooting indoors.
Fur Is The Word
Besides a microphone wind screen, when you shoot in the next-level environments with more wind, you’ll also need a fur windshield. The hairs on a fur windshield perform a miraculous task; they break up about 80% of the wind buffeting sound when shooting exteriors. To take a windscreen and fur windshield to the next step, pro sound mixers will place the microphone into a zeppelin, a fully enclosed foam, cloth and or plastic capsule that completely isolates the microphone from wind noise and buffeting, unlike windscreens, which typically only cover the front of a microphone but leave the rear of the microphone exposed. Zeppelins are larger, heavier and more expensive, but when combined with a full fur windshield, provide usable audio in even the most windy and intense weather.
The next part of the audio chain is your microphone mount. There are many ways to mount a microphone and wind protection to a boom pole. Some are relatively expensive and elaborate. Others are inexpensive and simple. Think of a microphone mount like the suspension on your car. It’s intended to shield the microphone from handling noise, bouncing the pole around being picked up in the recording. Another consideration is ease of position adjustment. Think about it; if you’re hand-booming a scene, you may need to adjust the angle and attitude of the microphone, depending on where you’re holding the boom pole and where the talent is located at the end of your boom pole.
A sound mixer’s boom pole is an essential part of their kit. There are many different brands and materials for boom poles although the most common are made of aluminum, fiberglass and carbon fiber. Boom poles are also available in both internally cabled and externally cabled versions in several different lengths. Personally, I mostly use my boom pole to shoot interviews, where I can typically position the boom pole fairly close to the talent. I also travel quite a bit, so I wanted a small and light boom pole like my K-Tek travel pole, which is only about 7 feet long and folds down to a very short and easy-to-pack length. If I was planning on shooting more reality or narrative programming where you might have multiple cameras involved, some shooting wider angles, I would consider a longer, more heavy-duty boom pole, something in the 10 to 14-foot length.
Boom Pole Mounts
Boom poles are typically deployed handheld for scenes where the camera and/or talent are moving or mounted to a C-stand or light stand for sit-down interviews and other stationary narrative scenes. So how do you rig a C-stand or light stand to hold a boom pole for you? Of course, you use a boom pole holder. A boom pole holder looks very similar to a fishing rod holder used for shore fishing, a U-shaped metal bracket designed to cradle a long tubular object. Some even literally use a fishing pole holder to hold their boom pole.
You’ll also need a grip head to attach the boom pole holder to your C-stand or light/microphone stand. Regular C-stand grip heads work well but are a bit large and heavy for travel. I found this Matthews composite grip head, which is smaller and lighter than a typical aluminum grip head. It’s also not as heavy duty so you have to not crack down on it too much to tighten it, or you can crack the head, but the weight and size savings are appealing.
Pro microphones utilize XLR connections, as do professional cameras and audio recorders. It’s pretty simple to buy a simple M-F XLR cable to connect your boom microphone to your camera or recorder. You should buy a longer cable than you think you’ll need; a 25-foot cable is a good choice for typical shooting. You should also buy a spare cable, as cables do develop shorts and go bad, and if you only have one cable on a shoot, you’re in bad position. You should also choose high-quality cables made with good-quality connectors; this isn’t the time to cheap out. Good XLR cables last decades, if well taken care of. Figure $40 to $60 each for high-quality 25-foot XLR cables.
The End Of the Line
Although you may not realize it, by this point, you’ve assembled your first audio chain. You’ve bought a shotgun or cardioid microphone, and added wind protection, a mount, boom pole, boom pole mount and a cable to take the sound from your boom pole to your camera or audio recorder. The audio chain is an important concept to understand because it can be extended and extrapolated to all kinds of other chains, like from your lavalier mics to a recording device, wireless lavaliers and from multiple microphones to the recording device.
Frankly, microphone booming is an art and a science that’s not easily mastered, but you can get better at it by simply practicing and listening. Pro boom operators wear headphones as they boom so they can hear exactly what the camera or sound recorder is recording, and they adjust the angle, height and orientation of the microphone accordingly, moving it farther from the talent when the talent gets loud or moving it closer to the talent as they speak softer or whisper. Boom mics are also used to record ambient, sound effects, music, gunshots and thousands of other things, so the best way to learn what works best is to practice and listen, listen and practice.
For booming people, the best possible location for the boom microphone is 12 to 18 inches over the head of the talent, with the actual microphone pointed at the talent’s chest, not directly at their mouth. Think about it; the microphone is picking up not only the talent’s voice but it’s also recording what’s around and behind the talent as well. By pointing the microphone element at their chest, rather than their mouth, you’re minimizing the amount of other sounds around and behind the talent. Makes sense, right?
Metering And Recording Devices
There are a few concepts here to understand. Most visually oriented users typically will be plugging one or two microphones directly into the camera. Professional cameras can supply the 48V phantom power at their XLR outputs that most professional microphones require. The sound metering on most cameras isn’t nearly as sophisticated as most pro-level sound recorders, but it will suffice if you understand what you’re looking at. It’s best to record sound at a nominal peak level, meaning that most of your sound averages out to a certain “nominal” level. You need to leave headroom for peaks for when your talent unexpectedly yells, screams or laughs, but you don’t want to record your audio at too low of a level, either, because it will require a boost to reach nominal output levels at the end when the final project is output for the web, broadcast or home video.
Pro sound mixers generally work at a nominal level of -20 dB, although many users find this level to be too low. Years ago, Apple, in Final Cut Pro, put in markers on the audio meters that reflected a nominal audio level of -12 dB, instead of -20 dB (the lower the number, the higher the signal). Many users now use -12 dB nominal as their standard audio input level, allowing peaks to reach as high as -6 dB. You should also remember that audio meters may not always be able to track audio transients well so you can reach clipping that you’ll hear as distortion but your meters not be able to react quickly enough to display the peaks. The most important meter are always your ears. If something sounds distorted, it probably is, even though your meters may not tell you.
Although this article is by no means an exhaustive study of every point of location sound recording, if you read carefully, you now have a good basic knowledge of what it takes to record quality audio from your boom microphone to your camera. Stay tuned for more sound-mixing and audio-recording technique content, both here and elsewhere on the hdvideopro.com website. HDVP
Writer, producer and cinematographer Dan Brockett’s two decades of work in documentary film and behind the scenes for television and feature films have informed his writing about production technology for HDVideoPro Magazine, Digital Photo Pro Magazine and KenStone.net. Visit danbrockett.com.