2. Audio Basics (Continued)6
Audio Basics
(Continued)

3. Feedback
If the performer uses and omni-directional mic and steps in front of the band’s speakers, a high-pitched squeal is emitted - feedback
Occurs when a microphone picks up the sound coming from a speaker that is carrying that mic’s signal

4. Feedback Created when: To stop: Sound enters the mic
Sound is transmitted to an amp
Signal from amp is sent to a speaker
Sound from speaker goes through the air and back to the mic
To stop:
Move mic away from speaker
Bury the mic in your armpit
Turn down the amplifier
Turn the speaker away from the mic
Determine what caused the feedback & take precautions.

5. Feedback

6. Hand-Held Mic
Mic designed to be held in the hand rather than placed on a boom or clipped to clothing
Also known as stick mic

7. Microphone Covers Often made of soft polyester or polyurethane foam
Inexpensive
Durable
Disposable
Can deteriorate over time
Tend to collect dirt and moisture
Can be used to distinguish one mic from another on a busy set

8. Boom A pole with a mic attached to the end
Can attach any type of mic as long as connectors will match
Goal is to have mic as close as possible to talent but not dip into the shot
Fishpole boom – must be physically held over heads
The term “boom mic” refers to HOW the mic is used and not a type of mic

9. Accessories - Blimps
Hollow wind screens surrounding mics to reduce wind noise
Usually made of a synthetic fur material
“Zeppelins”
“Windmuff”
“Dead Cat” or “Kitten”
They can cut wind noise by as much as 25 dB, especially low-frequency noise. The blimp is essentially a hollow cage or basket with acoustically transparent material stretched over the outer frame. The blimp works by creating a volume of still air around the microphone.
The hairs deaden the noise caused by the shock of wind hitting the blimp. A synthetic fur cover can reduce wind noise by an additional 10 dB

10. Discussion
Discuss ways to create your own boom that would not tire your arms so quickly.

11. Lapel Mic (Lav)

12. Sennheiser Lavs

13. Lapel Mic (Lav) Smallest type of mic worn by talent
Attached at or near the breastbone
Uses a small clip or pin
Cord is routed under the clothing to be less obvious (or may be wireless)
Most common is about the size of a pencil eraser

14. Mic Use Guidelines
Always treat mic like the ear of someone you care for
Do not shout into mic
Do not slap head of mic with your hand
Do not exhale or inhale directly through mic
Never put lips directly on mic
Never swing a mic by its cord
Never blow into mic
Strong bursts of air or loud noises can stretch a diaphragm out of shape or even break a diaphragm

15. Mic Use Guidelines
Hold mic firmly in your fist and keep hands and fingers still
Can produce a distracting sound
Place the knuckle of your thumb against the sternum of your chest
Common mistake is to point the mic at the subject when asking a question then at yourself when answering

16. Mic Use Guidelines (Continued)
Aim mic toward desired sound
Vocal Application Mic Placement:
Less than 6” away
Gives robust sound, emphasized bass, max isolation from other sources
6” – 2’ away from mouth; just above nose
Natural sound, reduced bass
8” – 2’ away from mouth; slightly off to one side
Thinner, distant sound; noticeable ambient noise

17. Discussion What type of mics should be used for the following?
Political speech
Recording studio
Broadway play
Sidelines of Super Bowl

18. Interviewing Children
Do not stand over them
Kneel or squat down to be at least at their eye level or, better still, below their eye level
Less likely to be intimidated
Makes a more pleasing photo shot
Child can also be raised to your level with a stool

19. Mic Cables and AC Cables
Keep them as far apart as possible
If they must cross, have them cross at 90 angles and place an object, such as a book or board, between them

20. Two Types of Signals
There are two types of signals a microphone can send:
High Impedance (HiZ)
Low Impedance (LoZ)
Inexpensive
Low-quality
Longest cable runs usually no more than six feet

21. Low Impedance (LoZ) Expensive High-quality
Can tolerate long cable runs
All professional television gear utilizes low impedance audio signals

22. Three Levels of Audio
Mic level – 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
Output of a CD player to input of an amplifier
Power level – Audio level from the output on an amplifier to the speaker

23. Three Levels of Audio Levels cannot be combined
“Mic out” must connect to “mic in”
“Line out” must connect to “line in”
“Power out” must connect to “power in”
Result is massive distortion or no sound at all

24. Mixers
Mic mixer – designed to combine signals into a single or dual-channel sound signal
Audio 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
Each signal coming in to either mixer is controlled with a potentiometer or pot.
A knob or slider control that regulates the strength of a signal

25. Potentiometer (pot) Mixer has a different POT for each audio input
The operator gauges the signal strength by watching a VU meter (volume unit meter)
puh-ten-shee-om-i-ter
Potentiometer -a device for measuring electromotive force or potential difference by comparison with a knownvoltage.

26. Volume Unit Meter (VU meter)
VU Meter takes two forms – The first looks like a car’s speedometer with a scale and needle to indicate signal strength, the second is a series of LEDs that light as the signal gets stronger.

27. Audio Requirements
Analog recording systems–VU meter reading of +3 to –3 dB
Digital recording systems–VU meter reading of about –20 dB
Audio engineer must wear full muff earphones that block out nearly all extraneous sounds except the recorded sounds
“Ear buds” are unacceptable
Do not assume that the LEDs on a VU meter are the same for all – read your manufacturers directions. Different colored LEDs mean different things.
To operate either mixer type
Activate the sound source. Play a CD or instruct the talent to talk.
Bring up a single pot until the sound reaches a desired level on the VU meters
Repeat for each individual microphone or sound source. All the pots are typically not adjusted identically. The pot running a naturally loud voice is set much lower than the pot for a soft-spoken person’s microphone. All background music should be relatively low or it drowns out the dialogue in the scent.
Bring up the pot labeled “master” to send the mixed signal out of the mixer to the recorder.
The audio engineer makes certain that the signal has appropriate readings of +3 to -3 for analog and -20 for digital.

28. Audio Requirements
Whenever monitoring the master VU meter, never allow the needle to touch the far right edge
Called “burying the needle” or recording “in the mud”
Means the audio is being over-recorded
Aka – distorted
Cannot be fixed in post-production
Requires a retake – meaning $$$
Do not assume that the LEDs on a VU meter are the same for all – read your manufacturers directions. Different colored LEDs mean different things.
To operate either mixer type
Activate the sound source. Play a CD or instruct the talent to talk.
Bring up a single pot until the sound reaches a desired level on the VU meters
Repeat for each individual microphone or sound source. All the pots are typically not adjusted identically. The pot running a naturally loud voice is set much lower than the pot for a soft-spoken person’s microphone. All background music should be relatively low or it drowns out the dialogue in the scent.
Bring up the pot labeled “master” to send the mixed signal out of the mixer to the recorder.
The audio engineer makes certain that the signal has appropriate readings of +3 to -3 for analog and -20 for digital.

29. Automatic Gain Control (AGC)
Defined as a circuit found on most consumer video cameras that controls the audio level during the recording process
If the sound being recorded is soft, the AGC turn the recording levels up
But this also increases tape hiss and background noise
If sound is loud, AGC turns the levels down
A poor circuit for analog recording
Sounds helpful but is a second behind “real time”
An excellent circuit for digital recording

30. Accessories - Headphones
Essential for sound recording
Lets you preview what your are recording to check the quality
Full-ear will block out extraneous noises

31. Sennheiser Headphones
Model HD280
Closed ear
¼” jack plug
Adjust headband to fit your head
To clean, use a soft, damp cloth

32. Accessories - Slates
A written video and/or audio identification of a component such as a shot, line of narration or sound effect
Provides a visual clue for postproduction
For video only – can use just paper or post it notes

33. Career Page
The Audio Engineering Society is the only professional society devoted exclusively to audio technology

34. Review Question
What is the one thing to be aware of when using wireless mics? Make sure your mics are not using the same frequency as other wireless mics in the facility.

35. Review Question
Name the four functions of audio and give examples of each.
Voice track: dialogue or voiceover
Music and sound effects: DVDs, CDs, Internet downloads
Environmental: wind blowing, traffic noise
Room tone: a room with no people

36. Review Question
Microphones have pick-up patterns. What is the name of the mic that picks up sound equally in all directions? Omni-directional

37. Review Question
What are the appropriate VU meter readings for analog and digital audio systems?
Analog: between +3 to –3 dB
Digital: about –20 dB

38. Glossary
audio mixer: A piece of equipment that takes the sounds from a variety of sources, such as mics, a CD player, or tape player, and combines them into a single sound signal that is sent to the recorder.
automatic gain control (AGC): A circuit found on most consumer video cameras that controls the audio level during the recording process.

39. Glossary
background sound: Type of environmental sound that is not the focus of or most important sound in a shot.
boom: A pole that is held over the set with a microphone attached to the end of the pole.

40. Glossary
boundary mic: A microphone used to pick up a sound on a stage or in a large room and is most commonly a condenser type. Boundary mics are usually placed on a table, floor, or wall to “hear” the sound that is reflected off hard surfaces.
cardioid mic: A mic with a pick-up pattern that captures sound from primarily one direction. Also called a uni-directional mic or directional mic.

41. Glossary
condenser mic: A type of mic that requires an external power supply (usually a battery) to operate. The generating element is a thin piece of metal foil or coated film. Also called an electret condenser mic.
dynamic mic: A very rugged type of mic that has good sound reproduction ability. The generating element is a diaphragm that vibrates a small coil that is housed in a magnetic field.

42. Glossary
feedback: A high-pitched squeal that occurs when a microphone picks up the sound coming from a speaker that is carrying that microphone’s signal.
fishpole boom: Type of boom that must be physically held over the heads of talent.

43. Glossary
generating element: A thin surface inside the mic that vibrates when hit by sound waves in the air and creates an electrical signal. Also called a diaphragm.
hand-held mic: A mic that is designed to be held in the hand, rather than placed on a boom or clipped to clothing. Also called a stick mic.

44. Glossary
high impedance (HiZ): A type of mic that is typically inexpensive, low-quality, and cannot tolerate cable lengths longer than 8.
hypercardioid mic: A directional mic with a narrower and longer pick-up pattern than a cardioid mic.
lapel mic: The smallest type of mic that can be worn by talent and is attached to clothing at or near the breastbone with a small clip or pin. Sometimes referred to as a lav.

45. Glossary
line level: The level of audio between pieces of audio equipment. For example, the level of audio going from the output of a CD player to the input on an amplifier.
low impedance (LoZ): A type of mic that is costly, high-quality, and can tolerate long cable lengths.
mic level: The level of audio that comes from a microphone. It is designed to be sent to the “mic in” on a recorder or mixer.

46. Glossary
mic mixer: A piece of equipment that combines only the microphone signals into a single sound signal.
microphone (mic): The piece of equipment that picks up sounds in the air and sends them to the mixer or recorder.
natural sound (nat sound): Environmental sound that enhances a story and is important to the shot.

47. Glossary
off-camera narration: Program narration provided by talent that is heard, but not seen by the viewer. Also called voiceover (VO).
omni-directional mic: A mic with a pick-up pattern that captures sound from nearly every direction equally well.
on-camera narration: Program narration provided by on-screen talent (seen by the camera).

48. Glossary
parabolic reflector mic: A very sensitive mic that looks like a satellite dish with handles and is designed to pick up sounds at a distance.
pick-up pattern: A term that describes how well a mic hears sounds from various directions.

49. Glossary
pop filter: A barrier made of shaped wire covered with a piece of nylon that is placed between a sensitive mic and the talent to avoid damage to the diaphragm of the mic.
potentiometer (pot): A knob or a slider that controls the strength of signal.
power level: The audio level from the output on an amplifier to the speaker.

50. Glossary
ribbon mic: The most sensitive type of mic used in television. A thin ribbon of metal surrounded by a magnetic field serves as the generating element.
room tone: The sound present in a room or at a location before human occupation.
shotgun mic: A directional mic with an extremely narrow pick-up pattern.

51. Glossary
supercardioid mic: A directional mic with a narrower pick-up pattern than a hypercardioid mic.
voice track: The audio portion of a program created through dialogue or narration.
volume unit meter (VU meter): A meter on either an audio or mic mixer that indicates signal strength.

52. Glossary
wireless mic: A mic that uses a short cable to connect the mic to a radio transmitter with an antenna, or the transmitter may be built into the mic itself. The transmitter wirelessly sends the signal to the receiver, which sends the mic signal through a short cable to the recorder.