Audio Video Production Audio Basics

Transcription

1 Audio Video Production Audio Basics Copyright Texas Education Agency, All rights reserved. Images and 1

2 Sound Sound has two basic characteristics: Loudness - measured in decibels Frequency - measured in Hertz Copyright Texas Education Agency, All rights reserved. Images and 2

3 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 Rock Concert/ Gunshot Jackhammer City Street/ Restaurant Quiet Conversation Office Environment Whisper 30 Silent studio 20 Copyright Texas Education Agency, All rights reserved. Images and 3

4 Loudness dbm Unit of electrical power Measured with VU meters Digital VU meter Analog VU meter In live production, 0 is considered the maximum desirable sound level 0 is also called Unity In post-production, the audio levels are between -12 and -6 db. 0 should NOT to be reached 4

5 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 Copyright Texas Education Agency, All rights reserved. Images and 5

6 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) 6

7 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 7

8 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 8

9 Types of mics Ribbon microphone Uses a small ribbon (rather than coil) moving in a magnetic field Similar to condenser mics in pickup quality and sensitivity Produces warm, rich sound Very sensitive to rough handling and moving air Rarely used outside an audio booth LuckyLouie. RCA 44 Ribbon Microphone. 4 November < a44.png>. 9

10 How microphones hear Cardiod Omnidirectional Unidirectional Microphone Pickup Patterns Omnidirectional Picks up sound in all directions Unidirectional (cardioid) Focused hearing in one direction Cardioid - heart-shaped pickup pattern Hypercardioid - narrow pickup pattern with a long reach (for distances) 10

11 How mics are used? Handheld mic Lavalier (lapel) mic Boom (shotgun) mic Desktop mic Headset mic 11

12 Handheld Microphone Held by the talent Advantages Reporter can easily move it closer to interview Singer can control intimacy of the sound by holding it closer Field reporters need a dynamic handheld mic Singers - need condenser handheld Mics Disadvantages Can be distracting Talent s hands are not free Quality of sound depends on proper placement by talent 12

13 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 a mic Requires proper setup and placement Clothing may rub mic or muffle sound 13

14 Lavalier Microphone 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 and over the talent s shoulder near the collar Clip mic to lapel, collar, or button flap Use gaffers tape to keep the mic cable from moving 14

15 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 15

16 Desktop Microphone Microphone mounted on a small stand Used for fixed positions Often seen in: Game shows Speeches Board rooms Churches 16

17 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 17

18 Wireless Microphones Involves a microphone with a transmitter and a wireless receiver Can come in any style Lav, headset, hand Allows complete freedom of movement without wires Transmits through frequency bands UHF Least interference More expensive VHF Cheaper Most interference 18

19 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 19