Capture Of Sound Flashcards

1
Q

What does a microphone do?

A

Converts variations in air pressure (sound) into electrical energy

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2
Q

How does a Dynamic Microphone work?

A

● Movable coil is positioned in a magnetic field, attached to a diaphragm
● Sound enters, diaphragm vibrates
● Coil moves in magnetic field, inducing a varying electric current
● Called Electromagnetic induction

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3
Q

What is a diaphragm?

A

A thin piece of material that moves in response to the changes in air pressure

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4
Q

How does a condenser microphone work?

A

● Contain a capacitor (two charged plates)
● Sound causes a plate to vibrate
● Change in separation causes a change in capacitance, so a current flows

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5
Q

How sensitive is a condenser microphone?

A

Quite sensitive - effective capture of quiet sounds

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6
Q

What are dynamic microphones like price-wise?

A

Generally inexpensive

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7
Q

What’s the frequency response of a condenser microphone like?

A

Flat and accurate

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8
Q

What features make dynamic microphones good for live use?

A

● Can withstand high SPL/volume
● Resistant to moisture
● Does not require phantom power

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9
Q

True or False, condenser microphones are able to capture a wide frequency range?

A

True

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10
Q

Do condenser microphones capture a brighter or darker signal than dynamic microphones?

A

Brighter

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11
Q

Why are dynamic microphones suitable for bass instruments?

A

Limited high frequency response

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12
Q

What can be said about the dynamic range of a condenser microphone?

A

It’s wide

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13
Q

What type of microphone is better for studio work, condenser or dynamic?

A

Condenser

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14
Q

How does a ribbon microphone work?

A

● Sound vibrations disturb metallic ribbon suspended in magnetic field.
● Voltage generated proportional to movement of ribbon.

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15
Q

What sound does a ribbon microphone produce as a close mic?

A

A warm sound - emphasises low frequencies

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16
Q

What does phantom power do to a ribbon microphone?

A

It damages or breaks it

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17
Q

What does a pre-amp do?

A

Converts a signal into a workable line level

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18
Q

On a pre-amp, what does the pad control do?

A

Attenuates the gain by a set amount to prevent clipping

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19
Q

What does a High Pass Filter do?

A

Removes frequencies below the cutoff frequency

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20
Q

What does the ‘Polarity’ control on a pre-amp do?

A

Inverts the polarity of the signal

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21
Q

What does a polar pattern do?

A

Describes how a microphone picks up sound from around the capsule

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22
Q

What does omnidirectional mean?

A

Picks up sound from all around the capsule

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23
Q

Describe the polar pattern of a cardioid

A

Rejects sound from behind the microphone

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24
Q

What is a cardioid microphone best for?

A

Close-mic work

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25
Q

Describe the polar pattern of a hypercardioid

A

Picks up sound from in front of the capsule and gives some capture of those behind

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26
Q

What is a hypercardioid microphone best at?

A

Providing partial isolation from other instruments but capturing some of the ambience of the room

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27
Q

Describe the polar pattern of a figure-of-8 microphone

A

Picks up sound from in front of and behind the capsule

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28
Q

What are Figure-of-8 microphones best at?

A

Mid-side recording techniques to give a stereo image of the sound

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29
Q

What 4 ways can engineers avoid capturing unwanted background noise and spill?

A

● Ensuring performers wear closed-back headphones
● Keeping the monitor mix relatively quiet in headphones
● Using acoustic screens/isolation booths
● Making use of overdubbing and directional microphones

30
Q

What does frequency response mean?

A

The frequencies a microphone picks up

31
Q

How do we know how ‘true’ the captured sound from a microphone is by its frequency response graph?

A

The flatter the graph, the more ‘true’ the sound is

32
Q

What do peaks on a frequency response graph mean?

A

Those frequencies are captured louder than they are in real life

33
Q

What does transient response mean?

A

How quickly the diaphragm can move when disturbed by a vibration

34
Q

What type of microphone tend to have the fastest transient response

A

Small diaphragm condenser microphones as they have the lightest and easiest to move diaphragm

35
Q

Why do dynamic microphones tend to have a slower transient response?

A

Because the diaphragm is connected to a heavy coil, so it doesn’t move as quickly

36
Q

What will happen if the volume on an electric piano is set at a low level, and the audio interface gain is turned up to the maximum?

A

You will capture lots of hiss

37
Q

Why is it important to record at a good level?

A

To maximise the signal-to-noise ratio, but not loud enough that the signal’s peaks are clipped

38
Q

What is the signal-to-noise ratio?

A

The difference in volume between the signal you want to capture and the noise

39
Q

What will a poor signal-to-noise ratio mean?

A

Noise is more prevalent in the recording

40
Q

What is headroom?

A

The gap between the loudest peaks of your audio and the point at which digital clipping begins

41
Q

What is analogue soft clipping sometimes used for?

A

Adding warmth

42
Q

What does digital clipping sound like?

A

Harsh and unmusical

43
Q

What does ‘Z’ represent on equipment?

A

Impedance

44
Q

What are Lo-Z inputs normally used for?

A

Microphones

45
Q

What are Hi-Z inputs normally used for?

A

Instruments such as electric guitar and bass guitar

46
Q

What do DI boxes do?

A

Convert a signal at instrument level to microphone level

47
Q

What is the order of signal levels, quietest to loudest?

A

Microphone, Instrument, Line

48
Q

What will connecting a line level source to a microphone level input cause?

A

Distortion: the signal is louder than the input is designed to accept

49
Q

What type of connectors do microphone level signals tend to travel through?

A

XLR

50
Q

What connectors do line level signals tend to travel through?

A

Balanced TRS jack, or unbalanced phono

51
Q

What is the proximity effect?

A

The increase of low frequencies depending on how close the microphone is to the sound source - the closer they are, the louder the low frequencies are

52
Q

When is the proximity effect particularly apparent?

A

When recording male voices and acoustic guitars

53
Q

When can the oriximity effect be used positively?

A

Fir recording kick drums and bass guitars

54
Q

What can you do to reduce the proximity effect?

A

Use an EQ or High Pass Filter; Alter the microphone position, moving it further away

55
Q

What can be used to remove unwanted low or high frequency noise?

A

Filters

56
Q

What type of filters can be used to remove hiss?

A

Low Pass Filters

57
Q

What type of filters can be used to remove hum?

A

High Pass Filters

58
Q

What can be used to remove a specific frequency that is causing a problem?

A

A parametric EQ with a narrow Q

59
Q

What does it mean if 2 sound waves are in phase?

A

Their peaks and troughs line up

60
Q

What does waves being out of phase cause?

A

Destructive interference

61
Q

In what situation must phase be considered?

A

Any situation where you are using lots of microphones to record the same sound source

62
Q

In what situation is phase difference particularly problematic?

A

When you are recording using two microphones on opposite sides of a drum

63
Q

What is the difference between phase and polarity?

A

Phase implies a shift in time relative to an initial wave, Polarity refers to the reversal of two connections on a cable

64
Q

What does placing a microphone at different angles do?

A

Changes the range of frequencies that are captured

65
Q

What will placing a microphone on-axis do?

A

Capture a brighter sound

66
Q

What will placing a microphone off-axis do?

A

Capture a duller sound

67
Q

What is the difference between an active and a passive DI box?

A

Active DI boxes require phantom power or a 9V battery, whereas passive DI boxes do not

68
Q

What are plosive sounds?

A

Sounds with a strong initial transient (e.g. p, d)

69
Q

What can you use to reduce the impact of plosive sounds?

A

Use a pop filter

70
Q

How does a pop filter reduce plosive sounds?

A

By dispersing the air more evenly to avoid such a large and quick diaphragm movement