Audio Video
Production
Audio
Basics
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1
Sound

Sound has two basic
characteristics:


Loudness - measured in
decibels
Frequency - measured in
Hertz
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Loudness

dBSPL (sound
pressure loudness)



Measure of acoustic
power
Sounds we can hear
with our ears
135 dB is considered
“threshold of pain”
 Ears ring
 Point at which hearing
damage can occur
Sound
dBs
Jet
140-150
Rock Concert/
Gunshot
135-140
Jackhammer
85-90
City Street/
Restaurant
70-75
Quiet
Conversation
60-80
Office
Environment
45
Whisper
30
“Silent” studio
20
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3
Loudness



dBm
Unit of electrical power
Measured with VU meters



In live production, “0” is
considered the maximum
desirable sound level


Digital VU meter
Analog VU meter
0 is also called “Unity”
In post-production, the audio levels are between -12 and -6 dB.

“0” should NOT to be reached
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other multimedia content used with permission.
4
Frequency


Basic pitch of sound (how
high/low it is)
Audible (hearing) range:
20Hz - 20,000Hz



20Hz - extremely low pitch,
rumble
20,000Hz - extremely high
pitch, higher than highest
note of a violin
Common hearing range:
50Hz - 15,000Hz
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5
Acoustics

Most sound booths
incorporate different types
of soundproofing materials

Hard walls; tile floors will
allow too much
reverberation



Reverb - sound remaining
after the original sound
stops
Too much soundproofing
causes a dead, lifeless
sound
Ideal room for recording
and listening has freestanding, sound-absorbing
items (furniture, rugs)
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Types of mics

Dynamic microphone
 Uses a small coil that moves within a magnetic
field when activated by sound
 Pros:
 Rugged and durable
 Can withstand weather and rough handling
 Great for ENG (electronic news gathering)
 Low Cost
 No power necessary
 Cons:
 Larger and heavier
 Not the best choice for quality audio
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Types of mics

Condenser microphone
Has a plate that moves against another plate to produce a signal


Pros:




More sensitive
Better quality
Can be small
Cons:


Fragile and sensitive to shock
and temperatures
Needs power



Battery
Phantom power supplied by
camera or audio mixer
Expensive
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Types
of mics

Ribbon microphone





LuckyLouie. RCA 44 Ribbon
Microphone. 4 November 2007.
<http://en.wikipedia.org/wiki/File:Rc
a44.png>.
Uses a small ribbon (rather
than coil) moving in a
magnetic field
Similar to condenser mics in
pickup quality and sensitivity
Produce warm, rich sound
Very sensitive to rough
handling and moving air
Rarely used outside an audio
booth
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How microphones “hear”
Microphone Pickup Patterns
 Omnidirectional


Cardiod
Unidirectional (cardioid)

Omnidirectional
Unidirectional
Picks up sound in all
directions
Focused hearing in one
direction
 Cardioid - “heart-shaped”
pickup pattern
 Hypercardioid - narrow
pickup pattern with a “long
reach” (for distances)
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How mics are used

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Handheld mic
Lavalier (lapel) mic
Boom (shotgun) mic
Desktop mic
Headset mic
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Handheld
Microphone


Held by the talent
Allows for talent to control mic’s location





Reporter can easily move it closer to
interview
Singer can control intimacy of the sound by
holding it closer
Field reporters - need dynamic handheld
(rugged, durable)
Singers - need condenser handheld (better
sound quality)
Disadvantages



Can be distracting (takes up visual space)
Talent’s hands are not free
Quality of sound depends on proper
placement by talent
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Lavalier Microphone



Small, rugged, omnidirectional
Usually clipped to shirts six to
eight inches below talent’s chin
Advantages



Talent can move freely
Mic never moves
Sound is consistent

Disadvantages



Each on-camera subject
requires mic
Requires proper setup
and placement
Clothing may rub mic or
muffle sound
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Lavalier Microphone

“Dressing” lapel mics (hiding wires)

Under clothing




Have talent run microphone under
the shirt
Clip mic to tie, lapel, collar or button
flap
Careful of material rubbing mic or
obstructing sound
Outside clothing



Run mic up the back of talent
(outside clothing) and over the
talent’s shoulder near the collar
(under collar if possible)
Clip mic to lapel, collar, or button flap
Use gaffers tape (on talent’s back) to
keep the mic cable from moving
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14
Boom Microphone


Unidirectional mics
intended to pick up sound
without being seen on
camera
“Shotgun” microphone
mounted to the end of a
telescoping boom pole


Pole has shock-mount to
absorb all movement
Can be held above talent
or at low angle below
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15
Desktop Microphone

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Microphone mounted
on a small stand
Used for fixed positions
Often seen in:

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
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Game shows
Speeches
Board rooms
Churches
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Headset Microphone


Gives talent the freedom of
movement while keeping
the mic close to the mouth
Sometimes includes an
earphone for talkback



Important for loud arenas
and stadiums
Used by sportscasters,
musicians/performers and
public speakers
Small, wireless headsets
with no earphone are
sometimes called
“countryman” mics
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Wireless Microphones

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Involves a microphone with a
transmitter and a wireless receiver
Can come in any style


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Lav, headset, hand
Allows complete freedom of
movement without wires
Transmits through frequency
bands

UHF



Least interference
More expensive
VHF


Cheaper
Most interference
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18
Windscreens



Designed to let normal
sound frequencies
through and filter out
wind noise
Made of acoustic foam
rubber
Windsock


Used for shotgun mics
Ragged cloth that is
pulled over the
windscreen
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other multimedia content used with permission.
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