microphones

Question 1

what is a microphone?

Answer 1

a device used for converting sound waves into electrical energy

Question 2

what is the main purpose of a microphone?

Answer 2

to record or amplify a sound source

Question 3

name 2 different types of microphone

Answer 3

dynamic
condenser
boundary
ribbon

Question 4

how does a dynamic microphone work?

Answer 4

inside a dynamic mic there is a diaphragm and a coil. The diaphragm moves backwards and forwards through the coil when hit by sound, the force of the magnetic field on the coil induces an electrical current in the wire

Question 5

give 3 strengths of a dynamic mic

Answer 5

• inexpensive to make
• robust and reliable, withstand heat, cold and humidity
• no power supply needed
• good for high volume levels

Question 6

give 3 weakness of a dynamic mic

Answer 6

• will only work effectively up to 16kHz
• small sound output so lots of amplification needed
• you have to be close to the microphone
• poor transient response

Question 7

how do condenser/ capacitor microphones work?

Answer 7

it has two plates which vibrate to create a signal. The diaphragm plate vibrates backwards and forwards and the static charge between the two plates is disturbed causing an electrical current. A voltage is required across the condenser for this to work.

Question 8

how can the voltage be supplied to a condenser mic?

Answer 8

This voltage is supplied either by a battery in the mic or by external 48volts of phantom power

Question 9

give 3 strengths of a condenser mic

Answer 9

• very light in weight
• can pick up sounds higher than the human ear can
• can make virtually any sound polar pattern
• detailed, clear sound with good high-frequency response
• high output levels so less amplification needed

Question 10

give 3 weaknesses of a condenser mic

Answer 10

• can be expensive
• not robust so can be easily damaged and must be handled with care
• looses sensitivity if used in a humid environment
• needs an additional power source (either 48v phantom power or batteries)

Question 11

how does a boundary mic work?

Answer 11

in the same way as a condenser but contain a pressure capsule which detects small changes in the air pressure as sound travels around a room

Question 12

how does a ribbon mic work?

Answer 12

consist of a thin strip of metallic foil suspended in front of a magnetic plate. Sounds waves cause the foil to vibrate, producing fluctuations in the electrical current, creating the audio signal

Question 13

give 3 strengths of a ribbon mic

Answer 13

• produces warm rich sound
• can pick up sounds higher than the human ear can
• detailed, clear sound with good high-frequency pick-up
• extremely sensitive with good transient response
• high output levels so less amplification needed

Question 14

give 3 weaknesses of a ribbon mic

Answer 14

• can be expensive
• not robust so can easily damaged and must be handled with care
• not a portable microphone
• needs an additional power source (either 48v phantom power or batteries)

Question 15

briefly describe a polar pattern

Answer 15

cardioid - picks up most of the sound from the front axis of the microphone
hyper cardioid - is an even more frontwards directional pattern with minor rear spill
figure of 8 - picks up sound equally from both the front and the back of the mic
omni directional - picks up sound equally from every direction of the mic

Question 16

what are the two main kinds of microphone techniques?

Answer 16

ambient recording and close microphone technique

Question 17

what is the close mic technique?

Answer 17

implies that the mic is close to the source and captures the full colour of the sound

Question 18

what are some problems with close miking?

Answer 18

the proximity effect where the bass frequencies in a sound are more pronounces, generally this is caused by the mic being too close to the source

Question 19

what are the 4 main types of ambient recording?

Answer 19

• AB stereo pair/ spaced pair
• coincident pair or X Y pair
• Blumlein Stereo pair
• mid-side stereo pair

Question 20

what is a spaced pair of mics?

Answer 20

an exact pair of microphones spaced a minimum of 1 metre away from the source, placed and panned left and right of the sound source

Question 21

what is a coincident pair?

Answer 21

two microphones positioned with a 90 degree angle on top of each other, the centre of these two mics should be aligned with the sound source

Question 22

name the 2 audio recording methods

Answer 22

microphone

direct injection/input (DI)

Question 23

which recording method would you use to record a synth?

Answer 23

DI

Question 24

which type of mic would a vocalist use for a live performance?

Answer 24

dynamic mic

Question 25

which type of mic would a vocalist use for a studio performance?

Answer 25

condenser/ capacitor mic

Question 26

what is the difference between a mono and a stereo recording?

Answer 26

stereo means 2 channels (input or output)

mono means 1 channel (input or output)

Question 27

describe the meaning of overdubbing

Answer 27

to record additional tracks on to an existing recording

Question 28

during recording how do you control the amount of signal coming into the desk?

Answer 28

the gain dial

Question 29

describe 4 considerations when recording a studio vocal

Answer 29

• condenser mic
• cardioid polar pattern
• pop shield
• position = 10 to 30cms away from mic, singer on axis
• room ambient and isolation

Question 30

describe the process of double tracking

Answer 30

to record the same instrumental part twice in a real time environment

Question 31

describe normalising

Answer 31

increases the gain of an audio track

Question 32

what is the purpose of ambient miking?

Answer 32

to get a broader, natural sound from the source and to capture the ambients of the room or hall