Audio Basics

Audio Basics

Chapter 6

Television Production & Broadcast Journalism, 2nd Ed.

Ch. 6 ObjectivesExplain the function of audio for televisionIdentify the most common use of each type of microphoneUnderstand the importance of the pick-up pattern classification when selecting a microphoneRecall the appropriate VU meter readings for both an analog audio system and a digital audio system


Ch. 6 VocabularyAutomatic gain control (AGC)Background soundBoomBoundary micCondenser micDynamic micFishpole boomHigh impedance (HiZ)Lapel mic (lav)Low impedance (LoZ)Mic levelNatural (nat) sound

Off-camera narrationOmni-directional micOn-camera narrationParabolic reflector micPick-up patternRibbon micRoom toneShotgun micUni-directional micVoice trackWireless mic


The Functions of Sound for Television

Functions of sound for television:Voice trackMusic and sound effectsEnvironmental soundRoom tone


Voice TrackPrimary means of getting a message to the viewerConsidered the most necessary audio of a programSound created through dialogue or narration


Two Forms of NarrationOn-camera narration – viewer sees the narrator speakingOff-camera narration – viewer hears but does not see the narrator

Also called voiceover (VO)Narrator may be:

ReporterOn-the-street eyewitness


o Automatic dialogue replacement (ADR) – see Production Note on p. 133

o Music and sound effects help set the mood and enhance the action of a program.

o Complete silence is artificial and should rarely, if ever, be found in a TV program.

o Care must be taken to prevent the volume of environmental sound from becoming distracting.


Environmental Sounds1. Background sound – environmental sound

that is not the most important sound in a shotMust not overpower the foreground sound in a shot


2. Natural (nat) sound – environmental sound that is important to the topic of the storyMay be the most important sound in the shotUsually captured on B-roll, either before or after the shot containing the voice trackNat sound is environmental sound that helps call attention to what a reporter is sayingIt entices the viewer to continue paying attention to the storyOnly environmental sound that supports the story


Room ToneThe sound present in a room, or at a location, before human occupationThe “sound of silence” in the shooting environmentRecord at least three minutes of existing environmental soundUseful when editingEnvironmental (room tone) sound may be used to cover unwanted sounds in the background of a scene that were not noticed while shootingLess noticeable audio edit than if true silence were used


Sound FrequencyThree groups of sound frequency:1. Low-frequency (bass guitar, drum & tuba; bass

vocals)2. Mid-range (trumpets, clarinets, French horns;

alto & tenor vocals)3. High-frequency (flutes & piccolos; soprano

vocals)


MicrophonesMicrophone – the piece of equipment that picks up sounds in the air and sends them to the mixer or recorderHow microphones work:1. Sound waves in the air hit a thin surface inside the

mic (generating element or diaphragm) which vibrates2. The vibration moves a tiny wire back and forth

through a magnetic field creating an electrical signal3. This electrical signal is sent through the mic cable to

an amplifier or recorder


Mics can be differentiated by examining the frequencies of sound each best capturesSome mics pick up certain frequencies of sound better than othersAudio engineer’s goal – match the right mic to the right frequencies of soundAll microphones are not created equal – typically get what you pay forLow-cost gear often yields results that are less than satisfactory


Wired & Wireless MicsRefers to how the signal gets from the mic to the recorderWired mic - attached to the recorder by a cable

Very reliableGreatest disadvantage—the cables


Wireless mic - short cable that runs from the mic to a radio transmitter

Transmitter sends the signal through the air, via a radio wave, to a receiver that is on or near the recorderReceiver picks up the signal and sends it through a short cable to the recorderWireless mics not the best choice for all applications, however

Primary advantage – freedom of movementDisadvantage – prone to interference from other wireless devices at or near the same frequencies

Always keep a backup wired mic available


Dynamic MicrophonesVery rugged type of mic that has good sound reproduction abilityDesigned to pick up sounds best in normal speaking voice frequenciesNot designed to mic musical instruments or accompanying vocalsDo not pick up high- and low-frequency sounds as effectively as mid-range sounds of speech


Condenser MicrophonesMic that requires an external power supply (usually a battery) to operateCan pick up a greater range of sound frequencies than dynamic micsGood condenser mics are usually more expensive


Ribbon MicrophonesMost sensitive of all mic typesIn television applications, most commonly placed on a talk show host’s deskNow primarily used in music recording studiosExpensive disadvantage – fragility of generating element (diaphragm)Often must use a “pop filter” which protects the mic from explosive “t” and “p” sounds, catches moisture and rushes of air before they hit the diaphragm


Non-Professional Microphones

Microphone built into low-end camcordersShould not be used in professional recording scenariosVery limited pick-up rangeOften produces audio that sounds like the person speaking has a bucket over his headPicks up the grinding sound of the zoom lens motor, the rubbing or knocking sounds of the operator’s fingers and hands, and the sound of the operator breathing


Specialized MicrophonesBoundary mic

Most commonly a condenser type micBecoming the most common way to mic an entire stage or large room

Parabolic reflector micVery sensitive mic that looks like a satellite dish with handlesSensitivity of electronic parts directly related to the costOften seen on the sidelines of professional football games


Pick-Up PatternRefers to how well a mic “hears” sounds from various directions

Omni-directional mic – pick-up pattern that captures sound from nearly every (omni) direction equally wellUni-directional mic (cartioid) – pick-up pattern picks up sound from primarily one (uni) direction


In a noisy environment, a directional mic is a better choice for a narrator or reporterThe viewer may have a difficult time separating the talent’s voice from the background sounds if an omni-directional mic is usedHypercardioid mic – narrower and longer pick-up pattern than a cardioid micSupercardioid mic – even narrower patternShotgun mic – even more directional still (parabolic reflector mic is a shotgun mic)


Mics on the SetHand-held microphone

Designed to be held in the handCan be placed on a stand or boomSometimes referred to as a stick mic


BoomA pole that is positioned over the set with a microphone attached to the end of the poleThe goal is to get the mic as close to the talent as possible without dipping the mic into the top of the pictureFishpole boom – type of boom that must be physically held over the heads of talent

Lapel mic (lav or lavalier)Smallest mic worn by talentAttached about 6 inches from the mouthWired under clothing


Guidelines for Handling Mics

Never blow into a microphone Do not shout into a microphoneNever let anyone put their lips directly on the micDo not slap the head of the microphone to hear the muffled thump through the speakersDo not exhale directly into or inhale through the micNever swing a mic by its cord


Proper Use of Microphones

Do not place lips directly on the surface of the micWhen using a hand-held, hold the mic firmly and keep hand and fingers stillGet the mic close enough to your subject in an interviewWhen interviewing a child, get on his/her level Never place an audio or mic cable beside an electrical cable

Electrical cables produce magnetic fields which can cause interference in the audio signal


ImpedanceIn television, a microphone’s purpose is to create a signal that is sent through a cable to be recorded.There are two kinds of signals that mics can send:

High impedance (HiZ) – a typically inexpensive, low-quality mic that cannot tolerate a cable longer than 8’Low impedance (LoZ) – high-quality, more costly mic that can tolerate long cable lengths


Three Levels of AudioMic level – the level of audio that comes from a microphone

Designed to be sent to the “mic in” on a recorder or mixer

Line level – level of audio between pieces of audio equipment

Example – the level of audio going from the output of a CD player to the input on an amp

Power level – the audio level from the output on an amplifier to the speaker


MixersMic mixer – combines only the microphone signals into a single- or dual-channel sound signalAudio mixer – designed to take the sounds from a variety of sources such as mics, a CD player, or tape player, and combine them into a single sound signal that is sent to the recorder


Automatic Gain ControlA circuit found on most consumer video cameras that controls the audio level during the recording process

Works best when it is part of a digital camcorder as opposed to an analog recording situation


Critical NoteIt is critically important for whoever is recording the audio to wear a good set of headphones that cover the entire earThis is the only way to accurately monitor the quality of the audio being recorded

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Audio Basics