Careers in Television and Video Production: Audio and Microphones

When first entering a career in television or even film production, you will be working with a variety of similar microphones and audio-related equipment. If you work in an audio recording studio, the equipment becomes even more numerous. In this installment we will just examine common microphones (mics) you will most likely come into contact with. We shall begin with defining microphone impedance. Impedance simply means a restriction of the signal. Think of a garden hose with the water turned on. Placing your foot on the hose will restrict the flow, and by applying more pressure, you can even stop the flow of water. This is what impedance basically means.

In terms of mics and audio equipment, they are either low impedance or high impedance. Any audio device using mini-pins, or unshielded RCA cables is considered high impedance.1/4" 'phono' connections are rarely used in TV or film anymore, but they are also high impedance. As the name indicates, with high restriction the audio cable is only good for the length it is made. By adding extensions to a high impedance cable, you further restrict the signal, like applying more foot pressure to the garden hose. Add enough extensions to the mix and you will completely lose audio signal. Low impedance is more desirable in television and film, characteristic by their XLR, or 'canon' connections. For one, low impedance carries a clean, and noise-free audio signal. Second, having minimal (low) restriction, you can attach extensions to the shielded cables and lengthen them without signal loss. This comes in real handy when out on location. Low impedance mics only work with low impedance audio equipment. It is possible to take a low-impedance audio output from a playback device and rewire it for high impedance output (RCA), but you cannot take a high-impedance audio device (CD player, etc.) and rewire for low impedance playback device without conversion. Nor can a low impedance mic be used with high impedance equipment without some type of transformer to convert the signal.

To alleviate this confusion, an audio mixing console is used, but we will get to that later in this segment. Right now we will look at some of the more common mics used in the industry. One of the first mics that you will come into contact with in television is commonly known as a tie, or clip mic. Its actual name is a lavalier microphone. There are two types. One is a 'hard wire' condenser, requiring a battery. The other is a wireless, using a transmitter and receiver. It too is a condenser mic. The mics most of us are familiar with are commonly known as 'stick' mics. These are carbon-type mics, having a small diaphragm inside to capture the sound. The diaphragm on some stick mics is only covered with a steel mesh. These will give you a sharper signal. The more familiar stick mic is one that performers or speakers use. These have a globular mesh screen with a foam filter inside surrounding the diaphragm. The purpose of the foam is to protect the diaphragm from close proximity of the mouth. The sound is somewhat muffled from the foam, cutting wind noise to a degree, but the mic can handle bursts of volume without damaging the diaphragm.

Most stick or lavaliers are cardioid mics, with a heart-shaped pickup pattern. This means its best signal is picked up in front, and gradually drops off on the sides. When using a lavalier mic, this is important when placing it on your subject. It must be placed on the side that your subject will be turning their head to speak, like during an interview. If you know that the speaker will only be looking forward, it should be placed in the middle. Sometimes an old-fashioned table mic is used. This is usually a ribbon-type mic, and picks up sound from whatever is directly in front of it. A traditional overhead 'boom' mic is omni-directional, picking up the signal from all sides. Booms are mostly used in studios and on film location. In television and video, a mic that looks similar to a boom is called a shotgun mic. A shotgun mic is hypercardioid and very directional. A shotgun eliminates most sound coming from the sides, only picking up from the direction it is being pointed. They may also have a switch to slightly change the angle of the pickup pattern. A wind 'sock' is usually placed over a shotgun to further decrease any ambient noise. It is usually seen mounted on a field camera, but sometimes is used on a boom stand, although its effectiveness as replacement for a boom mic is minimal. There are many other types of mics, some costing a thousand dollars or more, but these are the more common mics you will be using in this industry.

If you are a camera operator, your only main audio concerns are volume and recording as clean of a signal as possible. On larger productions and in the studio, an audio mixing console, or board is normally used. An audio board's input capacity can range from four to thirty-two inputs and more, but they all function in the same way. Even today's computer mixer software has many of the same features their hardwire cousins do. They may look complicated, especially when using a 24 or 32-track board, but each track has simple components and are easy to use. Put simply, you plug in an audio source to an individual track, which has a variety of functions. Each track usually has several ways to plug in an audio source, normally XLR or 1/4" phono plugs. Some tracks may even have RCA input connections, so you can use high impedance audio devices. Most boards have what is called phantom power. This switch allows the board to use condenser mics without having to use a battery.

Larger audio boards can output, or send a signal to a multitude of destinations. In audio recording studios using 32-tracks or more, each output signal is sent and recorded to an individual track. In most cases though, audio mixer consoles in film, television and video generally send to two separate audio signals, occasionally four for editing, or five for surround sound. Each input track on the board is divided and controlled individually. Normally they all have matching controls. These control the incoming (receive) and output (send) signal in a variety of ways. Usually at the top there is a control to adjust the attenuation (trim) of the signal. This is used to adjust the overall volume of the track to unity. There is a mark (U) on the individual fader that is used as a setting guideline for volume. This is the unity setting. The volume of each track should be within the range of zero decibels (0db), indicated on the main VU meters. Sometimes each track has its own VU meter. Going over 0db will cause distortion in the signal. The preferred volume setting for each track should be unity. The trim control is used to adjust the track's volume, so that the track can be set at unity, and still meet volume requirements monitored on the VU meters. When working with eight or more tracks, it is easier to remember their unity setting than each of their individual volume settings.

Below the attenuation knob are two or more auxiliary return (AUX) controls. On the board there are inputs and outputs for each auxiliary, so that an effects processor (reverb, flange, noise reduction, etc.) can be 'looped' through for each track. The AUX knobs control the amount of each effect. Each track probably will have three or four equalization (EQ) controls. They control the high, middle and low frequencies, allowing you to shape the audio sound. Unless you are editing, these controls are usually set at the middle while recording audio. You want the purest (sometimes called 'dead') sound possible when recording. In most cases enhancements and effects can be added later in post. Below the EQ knobs is the pan control. Unless you are posting in stereo, and want to separate different tracks to create an audio spectrum, the pan control is usually set at the middle and the track is used a single signal. There is usually a mute button for each track. Once each track's volume is set accordingly, the track can be muted, or 'punched out'. This is especially important in productions such as newscasts where everything happens quickly. In such instances, you do not fade up the mic, you 'punch' it in and out as each anchor speaks. Depending on the audio board configuration, the mute button may also serve as a way to send the signal to a third or fourth main output, useful for multi-track recording or posting.

Finally, the individual fader for each track controls the volume. This is usually set to unity. There may also be a solo button to monitor the signal directly without enhancements. There may be other input connections and controls, but these are the basic components for each track. They are all sent to the master faders, controlling the main output of the board, usually there are two. There may also be a fader for the control room monitor or headphones. On multi-track boards there are usually source buttons to select which setting will be sent to the main output. When you break it down to these simple functions, an audio mixing board does not seem so intimidating. It only appears complicated depending on how many inputs there are. Many of today's higher end digital boards can be operated to perform a number of pre-programmed computerized settings and automations.

For the most part, understanding microphone fundamentals, knowing the basic components of an audio mixing board, plus the experience using them, will give you a valuable skill to add on your resume in the entertainment field. The skill offers other opportunities in employment, like studio recordings, soundtracks and Foley (sound effects) work. On a local level, employment can also be found with A/V crews, sound reinforcement companies (live sound) and radio stations. Audio recording is a whole art in itself, and going in this direction requires further study, but the basic applications are always good to know.