Capture Of Sound

Question 1

What does a microphone do?

Answer 1

Converts variations in air pressure (sound) into electrical energy

Question 2

How does a Dynamic Microphone work?

Answer 2

● 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

Question 3

What is a diaphragm?

Answer 3

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

Question 4

How does a condenser microphone work?

Answer 4

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

Question 5

How sensitive is a condenser microphone?

Answer 5

Quite sensitive - effective capture of quiet sounds

Question 6

What are dynamic microphones like price-wise?

Answer 6

Generally inexpensive

Question 7

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

Answer 7

Flat and accurate

Question 8

What features make dynamic microphones good for live use?

Answer 8

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

Question 9

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

Answer 9

True

Question 10

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

Answer 10

Brighter

Question 11

Why are dynamic microphones suitable for bass instruments?

Answer 11

Limited high frequency response

Question 12

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

Answer 12

It’s wide

Question 13

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

Answer 13

Condenser

Question 14

How does a ribbon microphone work?

Answer 14

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

Question 15

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

Answer 15

A warm sound - emphasises low frequencies

Question 16

What does phantom power do to a ribbon microphone?

Answer 16

It damages or breaks it

Question 17

What does a pre-amp do?

Answer 17

Converts a signal into a workable line level

Question 18

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

Answer 18

Attenuates the gain by a set amount to prevent clipping

Question 19

What does a High Pass Filter do?

Answer 19

Removes frequencies below the cutoff frequency

Question 20

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

Answer 20

Inverts the polarity of the signal

Question 21

What does a polar pattern do?

Answer 21

Describes how a microphone picks up sound from around the capsule

Question 22

What does omnidirectional mean?

Answer 22

Picks up sound from all around the capsule

Question 23

Describe the polar pattern of a cardioid

Answer 23

Rejects sound from behind the microphone

Question 24

What is a cardioid microphone best for?

Answer 24

Close-mic work

Question 25

Describe the polar pattern of a hypercardioid

Answer 25

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

Question 26

What is a hypercardioid microphone best at?

Answer 26

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

Question 27

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

Answer 27

Picks up sound from in front of and behind the capsule

Question 28

What are Figure-of-8 microphones best at?

Answer 28

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

Question 29

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

Answer 29

● 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

Question 30

What does frequency response mean?

Answer 30

The frequencies a microphone picks up

Question 31

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

Answer 31

The flatter the graph, the more 'true' the sound is

Question 32

What do peaks on a frequency response graph mean?

Answer 32

Those frequencies are captured louder than they are in real life

Question 33

What does transient response mean?

Answer 33

How quickly the diaphragm can move when disturbed by a vibration

Question 34

What type of microphone tend to have the fastest transient response

Answer 34

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

Question 35

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

Answer 35

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

Question 36

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?

Answer 36

You will capture lots of hiss

Question 37

Why is it important to record at a good level?

Answer 37

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

Question 38

What is the signal-to-noise ratio?

Answer 38

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

Question 39

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

Answer 39

Noise is more prevalent in the recording

Question 40

What is headroom?

Answer 40

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

Question 41

What is analogue soft clipping sometimes used for?

Answer 41

Adding warmth

Question 42

What does digital clipping sound like?

Answer 42

Harsh and unmusical

Question 43

What does 'Z' represent on equipment?

Answer 43

Impedance

Question 44

What are Lo-Z inputs normally used for?

Answer 44

Microphones

Question 45

What are Hi-Z inputs normally used for?

Answer 45

Instruments such as electric guitar and bass guitar

Question 46

What do DI boxes do?

Answer 46

Convert a signal at instrument level to microphone level

Question 47

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

Answer 47

Microphone, Instrument, Line

Question 48

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

Answer 48

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

Question 49

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

Answer 49

XLR

Question 50

What connectors do line level signals tend to travel through?

Answer 50

Balanced TRS jack, or unbalanced phono

Question 51

What is the proximity effect?

Answer 51

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

Question 52

When is the proximity effect particularly apparent?

Answer 52

When recording male voices and acoustic guitars

Question 53

When can the oriximity effect be used positively?

Answer 53

Fir recording kick drums and bass guitars

Question 54

What can you do to reduce the proximity effect?

Answer 54

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

Question 55

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

Answer 55

Filters

Question 56

What type of filters can be used to remove hiss?

Answer 56

Low Pass Filters

Question 57

What type of filters can be used to remove hum?

Answer 57

High Pass Filters

Question 58

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

Answer 58

A parametric EQ with a narrow Q

Question 59

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

Answer 59

Their peaks and troughs line up

Question 60

What does waves being out of phase cause?

Answer 60

Destructive interference

Question 61

In what situation must phase be considered?

Answer 61

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

Question 62

In what situation is phase difference particularly problematic?

Answer 62

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

Question 63

What is the difference between phase and polarity?

Answer 63

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

Question 64

What does placing a microphone at different angles do?

Answer 64

Changes the range of frequencies that are captured

Question 65

What will placing a microphone on-axis do?

Answer 65

Capture a brighter sound

Question 66

What will placing a microphone off-axis do?

Answer 66

Capture a duller sound

Question 67

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

Answer 67

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

Question 68

What are plosive sounds?

Answer 68

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

Question 69

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

Answer 69

Use a pop filter

Question 70

How does a pop filter reduce plosive sounds?

Answer 70

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