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Boom! Production Audio

In Chapter 3, we shared some basics on recording audio for a voiceover narration. Here we’ll show you what you’ll need to know about recording production sound, audio that occurs onscreen at the same time you’re recording the picture.

Any production sound you’ve included in your projects so far may have been recorded using the on-camera mic, the microphone built into the camera or one that is mounted on the camera. The sound you record from the on-camera mic can be useful for reference; it may also provide a great source of ambient sound. But when it’s important to hear what someone onscreen is saying, the closer the microphone is, the better. Doing so will take a few more tools and a crewmember dedicated to the job (see FIGURE 4.2).


FIGURE 4.2 The boom operator at work on a wide shot

Managing the Environment

Just as in the exercise in Chapter 2’s “Sound Design” section, notice the different sources of sound around you now. Even in a quiet space, we naturally tune out many sounds that a microphone doesn’t. If you’re a crew member in the sound department of a production, it can become a real chore managing the shooting environment to get the best sound possible.

Unlike humans, microphones and audio-recording devices are objective about the sound they hear and pick up. A microphone can’t tune out unwanted sounds, like we can, to focus on what’s important. One of your jobs during production, if you’re recording sync sound, is to make sure the only sound that can be picked up by the mic is what is most important onscreen.

Recording what is important does not mean recording every sound that would occur onscreen. Let’s elaborate. If you’re shooting a scene where two people are having a conversation in a café or restaurant, realistically there would be environmental sounds including the other patrons’ conversations, kitchen activity, servers moving around, music playing, and so on.

To get the best sound for the scene, every other sound other than the characters’ voices and movement should be silenced. By recording only the voices of your talent isolated from all other sounds, you will have complete control over the balance of volume levels in your sound design.

Then you can add the walla track and source music to your edit after the scene is cut together to maintain the illusion that the scene took place in one uninterrupted moment in time. Walla is the term used for the atmospheric sound effect of a crowd in a particular place. Source music describes music that would authentically be playing where the scene takes place, such as dance music in a club scene or elevator music in an get the idea.

Keeping your crew and background talent quiet is the easiest part of the job of managing the sound where you shoot. A harder task is making sure all fans and air-conditioning are turned off when the camera is rolling. In a tight space, with a lot of people crammed in and perhaps hot lights working like space heaters, this can contribute to an uncomfortable situation.

Here’s a question that may come up a few times during the low-budget production phase of your career: Does the air-conditioning really need to be off when you’re shooting? Yes. Yes, it does. The more noise you allow onto your production audio recording, the more filtering and loss of quality occurs to the audio in postproduction.

There are other common machines that we don’t think about frequently as being noisy, but they do make a difference in the quality of your audio. Look out for computers that aren’t required to be turned on or that will appear onscreen. Unplug any refrigerators nearby, but don’t forget to plug them back in during long breaks and when you wrap, or you’ll have very angry location owners to face and a terrible smell to deal with.

If you’re hearing unwanted sounds from a source outside of your direct control, such as a neighbor playing loud music, it’s time to meet someone new and make a friend. With your most sincere smile, go to the source of the sound you’d like to have stopped and ask ever so kindly if the source of the sound can be put on hold for the specific amount of time you need it to be off. Explain why it’s important to have the area quiet.

We believe most people on this planet of ours are basically good and will understand. Just make sure to thank whomever you asked once more to let them know that the quiet is no longer required.

Which Mic When

When recording audio for a video project, there are a few different types of microphones you should be familiar with and know how and when to use them. Microphones are categorized using different criteria such as what use are they designed for, whether they require power, and in what pattern or shape they pick up sound.

“How Dynamic!”

One microphone most people are familiar with is a handheld mic used in public address systems (PA systems) and vocal music performances. These microphones are most commonly placed in the dynamic category, which means they do not require power to deliver sound to the recording device (see FIGURE 4.3).


FIGURE 4.3 A dynamic handheld vocal microphone


The reason these microphones don’t need power is because they’re designed to be positioned very close to the source of the sound. You may see these microphones used in news-style interviews, held by vocalists singing a song, or used by a public speaker talking to a large audience.

Aside from those examples, there aren’t too many other instances when it’s acceptable to see onscreen talent holding a microphone. Imagine an intimate scene with a couple passing a mic between each other when they need to speak.

For picking up dialogue while maintaining a high standard of sound quality and keeping the microphone out of the frame, there are some other microphones to consider.

“I Call Shotgun!”

A shotgun mic is one of the most essential tools of the audio recordist or mixer on a video production. These mics are so named because they have a long, cylindrical shape and are placed on a mount that has a handle similar to that of a firearm. Most often, they’re placed on a boom pole to get the mic close to the sound source, while keeping it out of the camera frame.

Shotgun mics (see FIGURE 4.4) are in the condenser category. Condenser microphones require power to operate. One example of power used for shotgun mics is phantom power, commonly at 48 volts (V), which moves like a ghostly spirit up from the recorder, or receiving end, through the same microphone cable that brings the audio signal back down. These mics are designed to pick up audio from a distance, which is why they are long and require power.


FIGURE 4.4 The Sennheiser MKH 416 shotgun microphone, the workhorse of the industry


Unfortunately, microphones can’t avoid unwanted sounds the way a camera can frame out unwanted objects, although some are built to be more discriminating than others. Shotgun mics are designed to be unidirectional, meaning they have a pickup pattern (or polar pattern) that allows the mic to pick up the sounds from a narrower angle or a single direction. By contrast, omnidirectional mics, like most handheld dynamic mics, pick up sound fairly evenly in all directions (see FIGURE 4.5).


FIGURE 4.5 Pickup patterns of an omnidirectional mic and a unidirectional mic

This is both an asset and a liability. There’s great advantage to a mic that muffles down sounds outside of the pickup angle. But it also requires careful and accurate placement of the microphone to ensure a minimally acceptable quality of sound.

“There’s Lava Here?”

Another microphone that you’ll find handy is one that can be clipped directly on the talent. It can be placed in a visible location, or it can be hidden. It is the lavalier microphone, or body mic (see FIGURE 4.6).


FIGURE 4.6 Wireless microphone kit with lavalier mic

The lavalier microphone can be hardwired or used as part of a wireless kit that consists of a transmitter, which stays with the talent in a pocket or is clipped to a belt or waistband, and a receiver, which is connected to the audio recorder or camera.

A lavalier mic can be either omnidirectional or cardioid. A cardioid lavalier requires careful placement on the subject. Considerable turns of the head can have an undesirable on-mic/off-mic effect.

When putting a mic on your subject, don’t be shy about asking the person to route the lavalier cable up through their top. It’s okay to see the clipped lavalier mic on a subject, but you don’t want to see the wire hanging down over the subject’s top.

A lavalier microphone has a clip for secure placement on clothing. Setting up which direction the clip opens might depend on whether the subject is male or female. The buttons on men’s and women’s apparel are different. For men, the buttons are on the right; for women, they are on the left.

“How Do You Hold This Thing?”

In most shooting circumstances, you will likely ensure the greatest flexibility in microphone placement by using a boom or boompole. A boom is an extension arm to a microphone stand, or a rod alone, to allow the placement of a microphone to be moved during the shot.

The boom operator is responsible for holding and placing the boom where it is needed without getting it into the frame and without creating any shadows in the shot. The boom consists of several parts: a fishpole, a shock mount, and the microphone itself.

A fishpole can have several telescoping sections that allow you to extend the pole to get the microphone into position.

Shock mounts (see FIGURE 4.7) are made in many varieties. Their purpose is to hold the microphone with elastic suspension to keep vibrations on the boom or stand from creating unwanted noise in the signal. Most shock mounts use rubber bands that need to be twisted to hold the microphone firmly in place.


FIGURE 4.7 Shock mount


Follow these guidelines to properly operate the boom (see FIGURE 4.8):

  • Place your control hand (right if right-handed, left if left-handed) on the bottom end of the pole.
  • Your other arm will be your weight-bearing arm, holding the pole as you would a billiard cue stick.
  • Hold your arms in a “U” shape and directly above your head.
  • The boom should remain parallel to the ground. If held diagonally, the pole might sneak into the corner of the frame and not be noticed by the camera operator.

    FIGURE 4.8

    FIGURE 4.8 Ideal form of operating boom

The job of boom operator requires stamina more than strength. Height and a good reach are helpful too. Operating boom also requires you to have dialogue memorized. In a scene with two people speaking, the microphone has to be pointed at the person who has a line before they speak. If you wait for someone to start speaking before turning the mic, then you risk the beginning of lines being off-mic.

Here are some more considerations when operating the boom:

  • When extending the fishpole, keep each section in equal lengths to balance the strain of the weight equally.
  • With twist locks, it’s best to start at the lowest section and then work up when extending. Start at the top and work down when shortening.
  • If you need to extend the pole to its furthest length, bring in each section about an inch from fully extended to keep the locks from straining.
  • When not in operation, collapse the fishpole and place it horizontally on a flat surface. Leaning a fully extended boom on a wall is asking for trouble.


Connecting a microphone to a camera or audio recorder requires use of cables. The most common cable used in professional audio recording is a cable that has XLR connectors with three pins at each end. XLR connectors allow for a balanced audio connection and therefore longer-distance runs with less noise in the signal. A cable with XLR connectors (see FIGURE 4.9) is required for phantom powering a microphone.


FIGURE 4.9 XLR connectors

A cable is made up of wires. Each wire is made up of thin strands of copper. This design allows for flexibility of the cable, which is why you can loop cables in circles or lay the cable down flat on the ground. The tiny strands in the wires in the cables can break, especially if the cable is wrapped poorly or the cable is bent at sharp angles. The more breakage in the wires, the less quality the signal of audio will transmit. When enough of the strands in a wire breaks, a complete loss of signal occurs, resulting in a short.

To avoid damage to your delicate audio cables, wrap the cables in even and consistent loops, avoiding any figure-eight shapes, knots, or bending. The over/under method of cable wrapping is ideal.

So, if wire strands make up wires and multiple wires make up cables, what happens when two cables are combined into one? You’ve got yourself a duplex cable. A duplex cable has two connections, which allows a boom operator to have a single, beefier cable running to the recorder.

One connection is for the microphone; the other is for the boom operator’s headphones so that they can monitor the audio being recorded. Duplex cables designed for boom have a box with a belt clip (see FIGURE 4.10).


FIGURE 4.10 Duplex cable for boom

When recording audio on a mobile device, a consumer camcorder, or a DSLR camera, you will likely use cables that have mini connectors, also called mini phone connectors, that have a diameter of 3.5mm or 1/8”. For two-channel stereo connections, the 3.5mm connector is called a mini TRS connector. These are the same connectors used for consumer headphones and earbuds. Another variety of this connector, the kind used for mobile phones that have a built-in microphone, is called a TRRS connector.

All of these connections are unbalanced audio connections and cannot support phantom powering the microphone. When using these connections, the microphone must be either dynamic or powered by another source, like an AA battery.

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