Flashcards in Chapter 9 Deck (22):
1
Transducer
changes energy from one form to another
-in a microphone, changes sound waves to electrical
2
Dynamic Mics
-Moving coil microphone
-Mylar diaphragm attached to a voice coil
-movement within the magnetic field produces voltage in the coil which becomes the output signal
-Electromagnetism produces the signal
-do not require external power sources
-generally inexpensive
3
Ribbon Mic (Velocity)
Ribbon like metal placed between two poles of a magnet
-Ribbon vibrates between the magnetic poles when struck by sound waves creating a small amount of voltage in the ribbon
-Voltage in the ribbon becomes the output signal
-Sensitive to shock, fragile, large size
4
Condensor Mics
-Capacitor-electrical component with two electrodes (+and -)
-Variable Capacitance-diaphragm and backplate act as the electrodes of a capacitor
-Sound waves strike the diaphragm, distance between two electrodes changes producing a charge in the capacitance
-Requires power
-Electret Condenser- small microphone that does not respond well to high frequencies
-Phantom Power (+48V)-power supplied to the microphone along the same cable as the audio
-More fragile, expensive, more sensitive, have a better frequency response, and do not respond as well to sudden higher noises when compared to Dynamic microphones
5
Polar Response Charts
pickup patter of a particular microphone
-head of the microphone is at the center of the chart
-sounds from top are on-axis
-sounds from side are off-axis
-Major polar patterns are
6
Frequency Response
omnidirectional: picks up sound equally from all directions
-More directional at higher frequencies(point at source)
-unidirectional-pickup sound from only one direction
-reduce background noise reverberation from off axis sounds and excessive reverberation
-cardioid patterns: super cardioid, hyper cardioid, cardioid
-bidirectional: picks up sound equally from two directions
-figure eight
-ribbon microphones usually have a bidirectional polar response
7
Impedance
amount of resistance a signal encounters in a microphone circuit
-more impedance = less signal
-overload-too much signal, sound is distorted
8
Handheld Mics
dynamic or condenser
-can gather sounds quickly from multiple sources
9
Mounted Mics
studio or shotgun mics
-Studio: large microphones that are typically not moved
-Shotgun: mounting the mic on the camera, boom stand, or fishpole
10
Lavaliere Mics
usually condenser
-acceptable appearance on camera
-most use AA batteries
-Omnidirectional pattern usually
11
Multiple Application Mics
change configuration using switches
12
Wireless Mics
AKA Radio frequency microphone
-prone to interference
-they have two frequency ranges
13
UHF
Ultra High Frequency
-radio frequency electromagnetic waves: 300 mhz – 3 ghz
-broader audio channels = higher fidelity (high quality)
14
VHF
very high frequency
-Radio frequency electromagnetic waves: 30 MHz – 300 MHz
15
Pop Screen
Helps with Plosives
16
Balanced Audio Lines
Mic signal is carried by two leads instead ofone
-Shield is the ground, conductor leads are isolated from other electrical component
-Less susceptible to RF interference and hum
17
Unbalanced wires
Typically found on consumer level products
-Single conductor carrying the positive signal and a shield carrying the negative signal of the circuit
18
XLR inputs
Cannon connectors
male and female ends
-1/4 inch and 1/8 inch
-May lose audio frequencies on long wires
-Amplification to the line level helps reduce the loss of signal
19
Filters
high pass filter: reduces bass and rumble by cutting out low frequencies
-low pass filter: reduces hiss by cutting out high frequencies
-switchable attenuator pad-reduces impedance by 15, 20, 25, dB to avoid overload distortion
-Line Adapter: reduces line level to mic level
-Presence Adapter: slight boost in upper midrange frequencies to improve the intelligibility
-Response Shaper-slight dip in midrange frequencies to reduce sibilance
20
NAt sound
background Audio natural sounds
21
Room tome
Natural sound of room - ambience
22