Home Planning Roll Sound: How to Use a Boom Mic

Roll Sound: How to Use a Boom Mic

by Celtx

Even the most beautifully shot, expertly edited video can be sunk by bad sound: as the old adage goes, audio is 90% of video. In the era of easily accessible, user friendly camera equipment and post-production software, recording quality sound can often fall by the wayside – many teams don’t realize how important it is until they don’t have it.

The first step in securing good sound is acquiring a good microphone and learning how to use it. In this post, we’ll discuss the basics and best practices of employing the most quintessential microphone setup in film & video production: the ubiquitous boom mic.

What Is a Boom Mic?

A boom mic is any kind of microphone attached to a specialized extendable pole (AKA the boom pole), which is then wielded by the boom operator. Typically, the microphone attached to the boom is of the shotgun variety. Shotgun mics are ideal due to their narrower pickup patterns: this means they are more sensitive to sound emanating from in front of them, allowing you to point the mic at what you want to record while reducing off-axis sound. They are probably the most common type of microphone that you will encounter – for a more in-depth guide to shotgun mics, Sam Mallery at B&H offers an excellent guide on different makes, models, and power solutions.

BH shotgun mic

Click here to read Sam’s A to Z guide on shotgun mics.

1) Proper Form

Generally, you want to hold your boom pole over and slightly in front of your head, level to the ground and parallel with your shoulders with a firm overhand grip. Positioning your grip towards the middle of the pole makes it easier to keep it held up, so feel free to give yourself a little extra extension on the pole to accommodate this. Any time you move your hands on the pole you risk creating vibrations that will be picked up by the mic in the form of low, unpleasant rumbling, so make sure you are comfortable before the cameras roll. The microphone cable can also generate unwanted sound as the boom is moved around, so using a boom pole with an inline cable is always preferable. If your cable is external, pick up any forward slack and gently wrap it around the fingers on your lead hand and loop any remaining slack lightly around the base of the pole. Avoid making things too tight – operating a boom is all about subtle, fluid movement.

2) Where to Put It

The whole point of the boom is getting the microphone as close to the sound as possible. For recording dialog, you want to position the microphone above and slightly in front of the subject’s head. Try to maintain a constant distance from the subject: if the distance changes, so will the sound levels. As discussed above, you’ll most likely be using a shotgun mic with a directional pickup pattern – this means that you need to keep the tip of the microphone pointed directly at your subject’s mouth.

During any setup, communicate with your camera operator to determine the frame. This is the line that you need to keep the microphone above to prevent it from dipping visibly into the shot. You don’t always need to have your feet on the ground either – if there’s something safe to stand on top of to give yourself some needed clearance, use it.

3) How to Move It

Smoothly and carefully. Any sharp or jerky movements will more than likely create unwanted noise on the track. Never overextend yourself when moving the boom – if you’re not comfortable or are losing balance, adjust your setup and start again from the top. If you need to record multiple subjects, say a two-hander dialog scene, rest the boom pole on the purlicue (the space between your thumb and forefinger) of your lead hand and use wrist action with your other hand at the base of the pole to tilt the tip of the mic between subjects. Most importantly, be aware of your surroundings: boom poles can get heavy and some extend well beyond ten feet – you don’t want to swing one into a light stand (or an actor).

4) Knowing Your Scene

This all leads to the most important aspect of operating a boom: blocking and rehearsal. You’ll need to know exactly where the actors and camera are going, and be able to stay close to both while simultaneously staying out of their way. This takes careful planning and a lot of practice. Pay close attention as the scene is blocked, memorize the positions of everything (marks, lighting setups, the camera, props, cables, set dressing) and figure out how to avoid interfering with them – even your shadow can ruin a take. Know the script and get in tune with the actors as they rehearse so that you’ll know when to tilt the mic and capture the next line of dialog.

The key here is teamwork. Always be engaged with your crew and work in tandem. This is a critical channel of communication that goes both ways: when you’ve got your headphones on, you may find yourself aware of things that they are not: a noisy air conditioner, a passing airplane, or any other kind of unwanted interference. It’s always better to address these things before a take than to try and fix them in post. If you’re just not able to safely and effectively record a given setup, let your crew know so they can work out a solution.

In Conclusion

As with anything else, practice makes perfect. Experiment with and fine-tune your equipment and technique before you go to set, get familiar with the capabilities of your mic, and get comfortable with your movements. While it can be a nerve wracking experience at first, when you get the hang of it you’ll find yourself to be an indispensable part of any production team. At the very least, it’s a great workout.

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