Stereo Mics / Decca

Question 1

who was clement ader

Answer 1

1881 - connected series of telephone transmitters to the stage at Paris opera

Question 2

when was the first accidental stereo recording

Answer 2

1932 - RVA victor. result of noticing the balance of two seperate recordings of same performance

Question 3

when did bell labs record and transmit stereo sound

Answer 3

1932 - harvey fletcher

Question 4

when did stokowski first record in stereo

Answer 4

1932

Question 5

when did alan blumlein visit the cinema and file stereo patenent

Answer 5

1931

Question 6

what is omnidirectional polar pattern

Answer 6

equally sensitive to sound arriving from all sides. high end lift at the front and low sensitivity at the rear

Question 7

what is cardioid polar pattern

Answer 7

approx 6dB less sensitive to sounds arriving from the sides. Approx 15 to 25 dB less sensitive to sounds arriving from the rear

Question 8

what is hypercardioid polar pattern

Answer 8

approx 12 dB less sensitive to sounds arriving from the sides. two null points at +/_ 110 degrees of axis

Question 9

what is supercardioid polar pattern

Answer 9

approx 9dB less sensitive to sounds arriving from the sides. two null points at +/_ 125 degress of axis

Question 10

what is bidirectional (figure of 8) polar pattern

Answer 10

most sensitive to sounds arriving from the front and back. rejects sounds coming from the side.

Question 11

what is the optimum playback environment speaker position

Answer 11

speakers positioned 60 degrees to listening position forming an equilateral triangle. hard left and right between speakers are considered -30 and + 30 degrees.

Question 12

what is angular distortion

Answer 12

angular distortion represents the angular linarity of reproduction, that is the relative position of individual sources within the stereophonic recording angle when reporduced in front of the listener

Question 13

what to consider in stereo recording

Answer 13

distance

overall perspective

differential perspective

direct sound

early reflections

reverberation

Question 14

what is an AB pair

Answer 14

two identical space microphones, parallel to each other

Question 15

how is the localisation of an AB pair determined

Answer 15

by the time difference of signals from each mic

Question 16

what type of mics to AB pairs generally use

Answer 16

omnidirectional

Question 17

what is a problem with AB pairs

Answer 17

can cause an unfocused image, and generally have poor mono capability

Question 18

what is an XY mic placement

Answer 18

two directional mics mounted at right angles to each other with capsules placed exactly above the other

Question 19

how is the localisation of an XY pair determined

Answer 19

by the level difference of signals reaching each mic

Question 20

is there a timing difference between XY pairs

Answer 20

no

Question 21

what are the outcomes of an XY pair

Answer 21

solid centre of image, therefore very mono compatible. sharp and detailed image

Question 22

what is a problem with an XY pair

Answer 22

struggle to deliver wide spread

Question 23

what are the benefits of near coincident pairs

Answer 23

they provide a wider, more accurate stereo field.

give a sharper image and a greater sense of spaciousness.

minimal angular distortion

Question 24

what is an ORTF near coincident pair

Answer 24

2 directional microphones usually cardioid

17 cm apart

angled at 100 degrees

Question 25

what is an NOS near coincident pair

Answer 25

2 directional mics usually cardioid

capsules are space 30cm apart

angled at 90 degrees

Question 26

what is an DIN near coincident pair

Answer 26

2 directional microphones usually cardioid

spaced 20 cm apart

angled at 90 degrees

Question 27

what is an OSS near coincident pair

Answer 27

two omnidirectional mics spaced 16.5cm apart

separated by an absorbant disk 28cm in diameter

Question 28

what is the faulkner array

Answer 28

two bi directional microphones pointing at a sound source 20 cm apart

parallel to one another

Question 29

what is a stereo boundary array

Answer 29

2 omnidirectional mics within a boundary construction

the boundary separates the left and right channels

Question 30

what is a dummy head/binaural

Answer 30

a near coincident array with omni mics mounted in ear

microphones set about 6.5 inches apart

Question 31

what is a blumlein coincident pair

Answer 31

2 directional mics angled 90 degrees to each other

facing left and right sides of a sound source

Question 32

what is a mid and side coincident pari

Answer 32

1 cardioid and 1 directional mic set at right angles to each other

cardioid mic panned centre

bidirectional mic signal duplicated to 2 channels with one phase inverted

Question 33

how is localisation of a source provided between two speakers

Answer 33

1 level difference between L and R
2 time difference between L and R
3a combination of both level and time difference

Question 34

which mic placement rely upon level differences for localisation

Answer 34

XY

Blumlein

MS

Question 35

which mic placement relies upon time differences for localisation

Answer 35

spaced pairs

Question 36

which mic placements relies upon both level and time differences for localisation

Answer 36

ORTF

DIN

NOS

Question 37

what dictates the stereo capture

Answer 37

the angle of mics and the distance between mics

Question 38

what is the stereophonic recording angle

Answer 38

the sector of the sound field in front of the microphone system which will reproduce a virtual sound image between the loudspeakers

Question 39

what is the extent of angular distortion determined by

Answer 39

polar pattern

microphone angle

distance between the mics