401 Audio Production Theory Exam

Front 1

Give the standard value for the SPEED OF SOUND in meters per second.

Give the formulae for calculating the speed of sound though air at a given temp

Back 1

344 METERS PER SECOND

C = 331 + 0.6 x T

*Where C is the constant and T is the temperature

Front 2

When adding or subtracting positive and negative numbers which rules apply?

Back 2

A negative + a negative is always a negative

A positive + a positive is

always a positive

Front 3

When multiplying or dividing positive & negative numbers which following rules apply?

Back 3

A positive number */÷

positive is a positive

A positive number */÷

negative is a negative

A negative number */÷

negative is a positive

A negative number */÷

positive is a negative

Front 4

When dividing a fraction by a fraction on the calculator you can use the fraction division function then change the ratio to a decimal using which button?

Back 4

The S : D Button

Front 5

Name the units of decimal measurement

and their values in number of zeros ?

Back 5

tera T 1000000000000 (12 zeros)

giga G 1000000000 (9 zeros)

mega M 1000000 (6 zeros)

kilo k 1000 3 (3 zeros)

hecto h 100 (2 zeros)

deca da 10 (1 zero)

deci d 0.1 (1 zero)

centi c 0.01 (2 zeros)

milli m 0.001 (3 zeros)

micro μ 0.000001 (6 zeros)

nano n 0.000000001 (9 zeros)

pico p 0.000000000001 (12 zeros)

Front 6

What is the common log base?

Back 6

10

Front 7

What happens to air pressure when there is a compression of air particles?

Back 7

It increases

Front 8

What happens to air pressure when there is a rarefaction of air pressure

Back 8

It decreases

Front 9

What is 1 Hz describing?

Back 9

1 cycle per second

1 Hz is the measurement of one complete cycle (or one oscillation) of the compression and rarefaction of the pressure.

Front 10

How long in milliseconds does it take before the ear perceives the delay between two sounds arriving as an Echo?

Back 10

35 ms

Front 11

What progression do Octaves follow?

Back 11

Each Octave is double the frequency of the preceding one

C0 = 16.352 hz & C1 = 32.703 hz

Front 12

What mathematical progression does frequency follow?

Back 12

Logarithmic

Front 13

What mathematical progression do harmonics follow?

Back 13

Linear

Front 14

The ear perceives the difference between the peaks and troughs of a sounds amplitude as what?

Back 14

Loudness

Front 15

What is RMS and what is it used for?

Back 15

Root Mean Square

Used to determine average level of a signal.

Front 16

What does the period of a wave describe?

Back 16

The amount of time it takes for one full cycle to take place

Front 17

What equation describes the relationship between the period and the frequency of a sound wave?

Back 17

T = 1/f

T=1/1 or 1 second

T=1/2 or 0.5 seconds

T=1/4 or 0.25 seconds / 250ms

T=1/8 or 0.125 seconds / 125 ms

T= 1/1000 or 0.001 seconds / 1ms

T= 1/ 20000 or 0.00005 seconds or 0.05ms

Front 18

In what two ways can wavelength be described?

Back 18

The distance travelled by sound during one period

The distance between any two consecutive corresponding points along the waveform.

Front 19

Which equation describes the relationship between wavelength and the frequency?

Back 19

C = F x λ

λ = Lambda (Wavelength)

Front 20

What does Phase describe?

Back 20

Phase is used to describe the amount of deviation from 0 degrees when two identical waveforms are occupying the same space

Or how far along its cycle a given waveform is. The measurement of phase is given in degrees, with 360 degrees being one complete cycle

Front 21

At how many degrees would an identical waveform be described as 'Out of phase' ?

Back 21

180 degrees (Inverted)

Front 22

What happens if you sum two identical waveforms together?

What would be the resulting increase in

decibels?

Back 22

Double the amplitude

+6 dB

Front 23

What is Pan?

Back 23

A change in amplitude between left and rightchannels.

Front 24

Describe comb filtering

Back 24

Comb filtering is the effect of alternating reinforcements /cancellations at different frequencies.

In signal processing, a comb filter adds a delayed version of a signal to itself, causing constructive and destructive interference. The frequency response of a comb filter consists of a series of regularly spaced spikes, giving the appearance of a comb.

Front 25

What equation do you use to calculate Phase shift?

Back 25

Ø = △t x 360 x f

Where

△t = Time difference (delay) in seconds

f = Frequency

ø = phase shift in degrees

Front 26

Approx. how far does a sound wave travel through air at room temperature in 3ms?

Back 26

1 meter

Front 27

What does the Sum and Difference rule

describe?

Use base frequencies 100 Hz and 150 Hz as an example

Back 27

The sum of 100 Hz & 150 Hz=250 Hz

The difference from 100 Hz & 150Hz=50 Hz

So if you combine 100 Hz and 150 Hz you will also hear the sum and difference frequencies:

50 Hz and 250 Hz

Front 28

Describe what a Beat Frequency is?

Back 28

2 oscillators set at the same frequency e.g. 1 Hz

Moving one oscillator +/- 1 Hz will result in you hearing a one second cycle effect.

Front 29

Describe the term 'Out of Phase'

Back 29

When two identical waveforms are summed with a degree ofphase shift equaling 180 degrees this is known as Phase cancellation or being

'Out of Phase'

This will mean two identical sine waves at 180 degrees would result in silence

Front 30

Describe the 5 higher harmonics of a fundamental frequency of 100 Hz

Back 30

100 Hz (f1)

f2 = 200 Hz / f3 = 300 Hz /f4 = 400 Hz / f5 = 500 Hz

Front 31

How many harmonics does a sine wave contain?

Back 31

None

Front 32

What type of harmonics does a sawtooth wave contain?

Back 32

even and odd harmonics at decreasing amplitudes

Front 33

What type of harmonics does a square wave contain?

Back 33

All odd harmonics at decreasing amplitudes

Front 34

What type of harmonics does a triangle wave contain

Back 34

All odd harmonics alternating in polarity with steeper decreasing amplitude than a square wave

Front 35

What is refraction?

Back 35

Refraction may be described as a change in direction as sound travels through different media (as discussed before, the speed of sound is dependent upon the temperature and the density of a medium)

Front 36

What is diffraction

Back 36

Can be described as the bending of sound around physical objects. The degree of diffraction depends upon the size of the object in relation to wavelength of a sound frequency.

Front 37

What is reflection

Back 37

When sound encounters a hard surface it will reflect or bounce off in a different direction. Depending on the shape of the said surface this change in travel direction

Front 38

How would a Concave surface affect the sound

Back 38

Tend to focus sound. A satellite dish orradio telescope is an example of a concave shape that reflects sound to a focalpoint.

Front 39

How would a Convex surface affect the sound

Back 39

Tend to scatter sound also known as diffusion. The royal Albert Hall has convex reflection treatment on the ceilingto scatter sound back toward the audience.

Front 40

How would a corner surface affect the sound

Back 40

Tend to send incident rays back to towardsthe general direction of origin.

Front 41

What is direct sound

Back 41

The shortest distance that sound needs to travelfrom the source to the listener

Front 42

Describe an Early Reflection?

Back 42

Sound that has reflected off one or two surfaces.

Front 43

Describe a reverb tail or cluster

Back 43

Sound that has reflected off numerous surfaces

Front 44

Is pitch psycho-acoustic or physical?

Back 44

Psycho-acoustic

Front 45

Is Frequency psycho-acoustic or physical

Back 45

Physical

Front 46

Is Loudness psycho-acoustic or physical

Back 46

Psycho-acoustic

Front 47

Is Timbre psycho-acoustic or physical

Back 47

Psycho-acoustic

Front 48

Is spectral content psycho-acoustic or physical

Back 48

Physical

Front 49

Is Amplitude Psycho-acoustic or physical

Back 49

Physical

Front 50

What happens to the perception of pitch when listening to very low frequencies?

Back 50

It becomes harder to identify / differentiate pitch at lower frequencies

Frequency with longer periods (LowerFrequency sounds) require longer note to determine pitch.

Front 51

Describe what a fundamental frequency is

Back 51

The frequency that determines the pitch reference.

Also known as the 1st harmonic

This is typically the lowest frequency present within the harmonic content.

Front 52

What is the 1st harmonic?

Back 52

Same as the fundamental frequency

Front 53

What is a 'Formant'

Back 53

An overtone that holds no simple mathematical relationship to the fundamental frequency but contributes non-pitch related spectral content to the sound.

Front 54

What is the A D S R of an envelope

Back 54

A = Attack

D = Decay

S = Sustain

R = Release

Front 55

Describe the Equal Loudness Contour

(Fletcher Munson curve)

Back 55

A scale (measured in units of Phons) describing the relationship between frequency and

perceived loudness. Human hearing is much more sensitive in certain frequency ranges

1kHz for example is perceived much louder at far lower Sound Pressure Levels (e.g. 10 phons) than say 60 Hz

Front 56

What type of electrical component could the human ear be described as?

Back 56

The Human Ear is a Transducer.

It converts one type of energy into another. In this case acoustic energy (sound pressure) arriving at the tympanic membrane is converted into electrical energy in the form of neurological impulses.

Front 57

What are the 3 energy states that are involved in the transduction of sound in the human ear?

Name the 3 bones situated within the middle ear that convert acoustic energy into mechanical energy?

Back 57

Acoustic Energy – Pressure fluctuationscollected by the Pinna and auditory canal (Outer Ear)

Mechanical Energy – Movement of earcomponents (Hammer Anvil Stirrup and tympanic membrane Oval Window) (MiddleEar)

Electrical Energy – Cochlear receives soundin the form of the vibrations from the middle ear components and then sends apressure wave to the stereocilia up to the Basilar Membrane which then directs the wave to the cell hairs and onto the brain in the form of neural impulses.

Front 58

What part of the human ear is mainly responsible for sound localisation?

Back 58

Pinna

helps to localise sound,neuro-plasticity can adapt to changes (for example losing the pinna or outerear) but this takes time.

Pinna is sensitive to high frequencies,less so to low frequencies.

Front 59

What is I T D ?

Back 59

Inter Aural Time Difference

This localisation mechanism relies on arrival time differences between two ears.

Does not well on very high or very lowfrequencies.

Front 60

What is I A D?

Back 60

Inter Aural Amplitude Difference

This localisation mechanism relies on amplitude differences between the two ears.

Front 61

Describe Spectral Differences?

Back 61

This mechanism relies on timbre differences between sounds arriving at two ears, this mechanism does not work well on very low or high frequencies.

Front 62

Describe the HAAS effect?

Back 62

Law of first wavefront precedence:

If two or more versions of a sound are produced the first version to arrive at the listeners position will in most cases determine localisation.

This remains true for delay times up to approx.50ms and it is applicable even when the second arriving version of the sound is approx. 15db louder than the first within the specific delay times.

Front 63

Describe the Doppler effect?

Back 63

Caused by a sound emitting object chasingits own sound wave producing pressure fluctuations and thereby shortening the wavelength.

As the sound wavelength is shortened the pitchwill increase and visa versa

Front 64

Perception of distance is affected when the early reflections arrive closer to or further away from the direct sound?

Back 64

Closer to the direct sound.

Front 65

Which Decibel scale deals with measuring acoustic energy?

Back 65

dB (SPL)

Front 66

Where does the word Decibel come from?

Back 66

Deci

meaning 10 to the minus 1 (or 1/10)

and

Bel

(The Decibel scale was invented by Bell Labs)

Front 67

Is the DeciBel a defined quantity or a reference?

Back 67

Decibels are a reference against something!

They are not a set defined quantity so for example -6dB means nothing in isolation.

It only has meaning when used in context to a referenced & measured quantity.

Front 68

What is the reference value of the dBV scale?

Back 68

1 V

Front 69

What is the reference value of the dBu scale?

Back 69

0.775 V

Front 70

What is the reference value of the dBm scale?

Back 70

1 mW

Front 71

What is the reference value of the dBw scale?

Back 71

1 W

Front 72

Which dB scale uses the common log for its measurement?

Back 72

dB w

dB m

10 log or common log is used when measuring power

Front 73

What dB scales use 20 log for its measurement

Back 73

dBV

dB SPL

dBu

dBm

Front 74

If we double the power of a dBw reading how many decibels of a difference will we increase by?

Back 74

+3 dBw

Front 75

If we double the voltage of a dB V reading how many decibels of a difference will we increase by?

Back 75

+6 dBV

Front 76

Sound pressure is described using which unit of measurement?

Back 76

The Pascal

Front 77

If I increase from 1 to 8 Pascals how many dB SPL of a difference am i increasing by?

Back 77

+18 dB

1 to 2 Pascal equals an increase of6dB(SPL)

2 to 4 Pascal equals an increase of6dB(SPL)

4 to 8 Pascal equals an increase of6db(SPL)

Front 78

What is the reference for the dB SPL scale?

Back 78

20 micropascals

0.000020 Pascal

Front 79

What is the formulae for determining dB SPL?

Back 79

M / R x 20log

The measured value divided by the reference value x log amount (the log amount is dependent in the type of dB you are calculating)

Front 80

What is the formulae for determining dBw

Back 80

M / R x 10log

The measured value divided by the reference value x log amount (the log amount is dependent in the type of dB you are calculating)

Front 81

When calculating dB values the measured value is always what?

Back 81

Where you are going to

Front 82

When calculating dB values the reference value is always what?

Back 82

Where you are starting from

Front 83

The SOL for prosumer equipment is?

Back 83

1.23 volts +4 dBu

Front 84

When calculating dB what in what order would you use the measured and referenced values?

Back 84

START (Where you are going from) =Referenced amount

ENDING (Where you are going to) = Measured amount

Front 85

Name the different dB scales commonly used in audio and their referenced values.

Back 85

dB SPL (Sound Pressure Level)

‘measured’ number iscompared to 20 μPa

dBV (voltage)

‘measured’ number is compared to1 V

dBu (unloaded)

‘measured’ number is compared to 0.775 V

dBm (milliwatts)

‘measured’ number is compared to 1 mW

dBw (watts)

‘measured’ number is compared to 1 W

Front 86

What is the S.O.L ?

Back 86

The Standard Operating Level

Front 87

What is the 0VL value for Semi Pro equipment

Back 87

-10 dBV

Front 88

What is the unity gain level for broadcast standard equipment

Back 88

Broadcast +8 dBu

Front 89

What is the S.O.L for Hi-Fi equipment?

Back 89

-10 dBu

Front 90

Describe Gain Staging?

Back 90

Gain staging is bringing all signals into the console at the same standard operating levels in order to keep the noise floor low and the signal to noise ratio (SNR) high.

Front 91

What does dBFS mean?

Back 91

Decibel Full Scale

This is the decibel scale used in digital audio systems.

Front 92

At 0 dBFS what is the dBu reading?

Back 92

+24 dBu

Front 93

1.23 Volts is described as what?

Back 93

'Pretty Good Line Input Level'

Front 94

What is the 0 dBV in dBu ?

Back 94

+2.2 dBu

so for example -10 dBv = -7.8 dBu

Front 95

The dBFS (Digital scale) is measured using what level metering type?

Back 95

The dBFS (Digital scale) is measured in PEAK.

Front 96

The dB u (analogue unloaded voltage) is measured using what level metering type?

Back 96

RMS (Average Level)

Front 97

The noise floor for analogue is approximately what dBu from 0VU

Back 97

-94dB

Front 98

How high can the noise floor be when using tape?

Back 98

-20dB

Front 99

What is the typical S.O.L levels for digital audio

Back 99

-18 dBFS

Front 100

Name the two types of level meter that would be typically found in a studio?

Back 100

Peak meter

VU (Volume Unit)

Front 101

What type of decibels are used to describe loudspeaker output level?

Back 101

Power decibels

They must always state amplifier power in watts

and also distance

e.g. 110 dbSPL @ 1 watt @ 1 meter

(Calculated using the 10log formulae)

Front 102

Which law is used to describe the energy loss

ratio of a loudspeaker powered by an amplifier at distance?

Back 102

The inverse square law

Distance / Power / SPL

Front 103

If two separate sound sources are used in

Parallel their combined level is described using what formulae?

Back 103

Sum dB = 10 log(10 dB1/10 + 10 dB2/10 +10 dB3/10 +10 dBn/10) 


Front 104

Name the three different dB weightings and their relative Phon values.

Back 104

dB a which is based on the 40 Phon line

dB b which is based on the 70 Phon line

dB c which is based on the 90 Phon line

Front 105

What is a PPM meter?

Back 105

PPM = Peak Program Meter

Front 106

Describe VU ballistics?

Back 106

Response time of the meter needle

VU meters can take up to 300 ms to respond

fully to level changes

Front 107

How much headroom should you leave in a mix to allow mastering

Back 107

-3dB

Front 108

Describe the purpose of a correlation meter

Back 108

This type of meter will display phase relationships between left and right channels so will involve time arrival differences as well as frequency analysis.

Generally if the meter stays in the blue or in phase position(+180) all is good. If in the red position or out of phase (-180) not good.

Front 109

How many samples are taken during 1ms of a 44.1kHZ recording

Back 109

44 samples

Front 110

Where is the tympanic membrane located?

Back 110

The Middle Ear

Front 111

Name the tube that provides equalisation of air pressure between the outer and middle ear?

Back 111

The eustation tube

Front 112

What are the latin words for the 3 bones of the middle ear?

Back 112

Malleaus (Hammer)

Incus (Anvil)

Stapes (Stirrup)

Front 113

What are the three bones located in the middle ear collectively known as?

Back 113

The auditory osscicles

Front 114

Which part of the inner ear is filled with liquid?

Back 114

The cochlea

Front 115

Which part of the inner ear is responsible for sending electrical impulses to the brain?

Back 115

The organ of Corti

Front 116

How many times per second do the nerve endings / hair cells fire and recharge?

Back 116

1000

Front 117

Describe the purpose of EQ

Back 117

EQ is Equalisation.

It is used for frequency dependent level control.

Front 118

What is Q?

Back 118

Q is the Quality factor or bandwidth of the

frequency attenuation / amplification

Front 119

Name the three simplest types of filter?

Back 119

High Pass Filter or HPF

Low Pass Filter or LPF

Band Pass Filter or BPF

Front 120

Describe what is happening when 'ringing' a

filter

Back 120

Ringing occurs when very steep curves are used

This results in resonance of the filter that will create aboost at the cutoff frequency

Front 121

What type of EQ would be used to cut or boost a narrow range of frequencies?

Back 121

A peak EQ also known as a bell EQ

Front 122

When any type of EQ is used what type of interaction is inevitably being introduced to the sound?

Back 122

Phase Distortion

Front 123

Name the frequency range of VLF or very low frequency.

Back 123

20 Hz to 40 Hz

Front 124

Name the frequency range of LF or low frequency.

Back 124

40 Hz to 125 Hz

Front 125

Name the frequency range of LMF or low mid frequency.

Back 125

125 Hz to 315 Hz

Front 126

Name the frequency range of MF or Mid frequencies

Back 126

315 Hz to 2 kHz

Front 127

Name the frequency range of HMF or high mid frequencies.

Back 127

2 kHz to 4 kHz

Front 128

Name the frequency range of HF or high frequencies.

Back 128

4 kHz to 10 kHz

Front 129

Name the frequency range of VHF or very high frequencies.

Back 129

10 kHz to 20 kHz

Front 130

Describe 'Masking'

Back 130

When two sounds compete for space in the same part of the audio spectrum they can obscure each other causing the sound to be 'Masked'

EQ can help to keep competing sound frequency ranges separated.

Front 131

What is the attenuation rate of a 1st order filter

Back 131

-6dB per octave (1 Pole)

Front 132

What is the attenuation rate of a 2nd order filter

Back 132

-12dB per octave (2 Pole)

Front 133

What is the attenuation rate of a 3rd order filter

Back 133

-18 dB per octave (3 Pole)

Front 134

What is the attenuation rate of a 4th order filter

Back 134

-24 dB per octave (4 Pole)

Front 135

What is the 'slope' 'order' or 'pole' of a filter describing?

Back 135

The rate of attenuation in dB per octave below the cutoff frequency.

Front 136

What is a Shelf EQ

Back 136

Provides even gain cut or boost from a specified turnover or shelving frequency

Front 137

What will be the result of using a low Q factor value

Back 137

A broader range of frequencies will be affected.

Front 138

What will be the result of using a high Q factor

Back 138

A narrower range of frequencies will be affected

Front 139

What is a Semi Parametric EQ?

Back 139

Offers non continuous control over the Q factor

There may be 1 or more pre defined selections for the Q factor value.

Front 140

What is a Fully Parametric EQ

Back 140

Offers full variable over the centre frequency Q bandwidth and Gain.

Front 141

What is a Graphic EQ

Back 141

Pre defined range

Variable Q factor

Front 142

How do you calculate the centre frequency?

Back 142

Multiply Octave 1 by Octave 2 then take the square root of the result.

Front 143

What 3 values do you require to calculate the Q factor?

Back 143

To calculate the Q factor you need.

The centre frequency (f0)

The low frequency (fL)

The high frequency (fH)

Front 145

With a given bandwidth how would you calculate the Q factor?

Back 145

Q = (f0) / (B)

Front 146

True or False.

A bandwidth of 1 octave will always be represented by the same Q factor?

Back 146

True

Octaves follow a non linear progression which means the shape will stay the same. This means a Q factor of 1.4142 will always represent an octave of bandwidth no matter what the Centre frequency.

Front 147

What formulae is used to calculate the Q factor?

Back 147

Q = Fc / B

Front 148

True or False

Q is inversely proportionate to the bandwidth and directly proportionate to the centre frequency?

Back 148

True

Front 149

What formulae is used to calculate Octaves?

Back 149

fH / fL = 2n

if fH = 554 Hz and fL = 440 Hz

554 / 440 = 1.26

log2 1.26 =3.33 (or one third of an octave)

Front 150

What formulae is used to calculate a specific musical notes frequency

Back 150

fH / fL = 2(x/12)

Here we use x/12 to determine the number of semitones we wish to

calculate the frequency for.

If I want to know what is the frequency of A#4 I can first use A4 (concert pitch) toget fLA4= 440hz fH / fL = 2 (1/12) = 466.16

So A#4 = 466.16hz

Front 151

Reverb is the simulation of what?

Back 151

The reflectivequalities of an acoustic

environment.

Front 152

What are the various stages of reverberation?

Back 152

Direct sound

Theshortest path sound travels from the source to the listener.

Pre Delay (First Echo)

Thetime between the direct sound and the first reflection

Early Reflections

Thefirst reflections arriving from all other angles

The reverberant field

Amountdepends on number of surfaces and obstacles

Front 153

Describe the effect of diffusion on reverb?

Back 153

Diffusion is caused by sound reflecting off an uneven surface.

The asymmetric reflections produced result in a less resonant reverberation tail.

A good example of a diffuse surface is a cave.

Front 154

Name four methods of producing

reverb.

Back 154

Reverb Chamber

Spring Reverb

Plate Reverb

Digital Reverb

Front 155

What is a convolution reverb?

Back 155

These work by using an Impulse Response (IR) which is arecording of the reverberation of a space or a plate for example.

Front 156

What does IPS mean on a tape machine?

Back 156

Tape speed measured in Inches per second

Front 157

What is Multi Tap delay?

Back 157

Multiple playback heads

Allows more delay repeating at differing intervals

Front 158

Describe Slap Back Delay

Back 158

Used heavily in the 1950s by artists such as Johnny Cash, Elvis Presley etc.

Characterised by very short delay time <100ms

Short feedback and some tapeflutter.

Front 159

How would you calculate the delay time for a song with a tempo of 120 BPM

The delay should be for crotchets (quarter notes)

Back 159

Δt = 60/BPM = 1 quarter note in 4/4

60/120 = 500ms

Front 160

How would you calculate the delay time for a song with a tempo of 130 BPM

The delay should be for quavers (eighth notes)

Back 160

Δt = 60/130 = 1 quarter note in 4/4

60/130 = 0.461 secs or 461ms

461 ÷ 2 (Halving the delay gives us eighth notes)

= 230.5ms

Front 161

What is an L.F.O?

Back 161

Low Frequency Oscillator

An LFO is a very low frequency sine wave which cannot be heard but can be usedto affect (modulate) another signal or set of parameters in the digital domain.

Front 162

What does ADT stand for

Back 162

ADT (Automatic Double Tracking)

ADT uses a second tape machine with a very short delay (<10ms) added to theoriginal with oscillating varispeed (this was first done manually laterelectronically with a VCO acting as LFO)

Front 163

Describe what a flanger does.

Back 163

Phase interactions / comb filtering with a varying delay time or a ‘sweepingfrequency’

Front 164

Describe the effect of a Phaser

Back 164

Very similar to a flanger except this effect is created using an all-pass filter whichdoes not effect amplitude of frequency but instead effects the phase of the signal.

Front 165

Describe the Chorus effect

Back 165

Designed to emulate the sound of multiple people (sound sources) playing thesame instrument at the same time. E.g. a Choir

Slight variations in time pitch and amplitude are used to mimic real chorus.

An LFO modulates delay time but with a longer delay than a flanger or phaser soas to avoid comb filtering.

Front 166

Describe how a Wah Wah effect is produced

Back 166

An LPF with a resonant peak (usually by ringing the cutoff frequency) moving up anddown the frequency spectrum.

Usually modulated by a pedal or an LFO.

Front 167

What is a Vocoder?

Back 167

The frequency response of a signal is super-imposed with the input of anothersignal. This is usually a vocal input.

Chords / Notes on a separate input aremodulated by the vocal input as both these signals each pass through first an LPFand then a series of BPF’s which are each set to a different frequency range

Front 168

Describe the 'Leslie' effect

Back 168

Produced by Rotary Speakers (Level and Filter based effect)

Produces a pan / tremolo / doppler type effect

Commonly used on Hammond Organs.

Front 169

What is a compressor?

Back 169

A compressor is a device that reduces the dynamic range of a signal

Compression is a form of dynamic processing.

Front 170

What are the typical controls found on a compressor

Back 170

Threshold

Ratio

Attack

Release

Gain

Front 171

What is limiting?

Back 171

Limiting is a form of soft clipping

A compressor with a ratio of 10:1 or higher is generally considered to be acting as a limiter.

Front 172

Describe the purpose of a side chain in a compressor.

Back 172

A side chain allows a separate input to act as the control signal for the compressors voltage controlled amplifier.

Front 173

What is the formulae for calculating compressed output?

Back 173

Compressed output =

Input - Threshold + Ratio

Front 174

What are the main reasons for using

compression?

Back 174

Dynamic range control

Add tone & colour (long release / reduce sustain)

Transient control (peak enveloping)

Add harmonic distortion / multi band

(frequency based amplitude control)

Front 175

What is the difference between a 'Hard Knee' and 'Soft Knee' compressor

Back 175

A hard knee compressor begins compression when the signal reaches thethreshold.

A soft knee compressor begins compression slightly before the threshold isreached and increases compression as the signal rises above the thresholdcreating a smoother curve.

Front 176

Describe Mid / Side (sum and difference)

Back 176

When combining two mono signals the same signal played in both speakers withno time difference but panned hard left and right will result in a centered or ‘Mid’ image

Conversely phase and time differences will result in the stereo imaging movingleft and right of the center or ‘Side’ imaging.

Front 177

When we 'De-Ess' a signal what frequency range do we remove?

Back 177

2kHz - 9kHz

Front 178

What does an 'Expander' do?

Back 178

An expander increases the dynamic range of a signal (opposite to compression)

Attenuation is applied to low level signals and it occurs according to a given ratio.

Front 179

Describe what a Noise Gate does

Back 179

Gating mutes the signal below a certain threshold.

Front 180

True or False

Microphones use very large voltage levels to send the input signal?

Back 180

False

Microphones use very small voltages

Usually Microvolts & Millivolts

Front 181

Describe the difference between an unbalanced and a balanced cable

Back 181

Unbalanced cables have a single common and return path. They are prone to noise and other electromagnetic interference.

Balanced cables have a dual path design utilising CMR (Common Mode Rejection) (+/- and ground)

This allows the signal to be split into positive and negative paths.

Signal on one and Noise on the other. When the two are phase inverted and summed the noise cancels and the signal is doubled (+6dB)

Front 182

Describe the three main properties of electricity as described in Ohms Law

Back 182

Current = Movement or flow

Voltage = Potential difference between two points of a circuit

Resistance = The opposition to current (this can be in the form of a wire likecopper or a light bulb)

Front 183

What is a DI box?

Back 183

DI (Direct Injection)

Takes an unbalanced (instrument level) input (1/4 inch jack) and outputs to a (line level) balanced cable

Front 184

What electrical element is analogous to audio?

Back 184

Voltage (Potential Difference)

It is analogous to the complete period of a sine wave (as compared against thepositive and negative terminals on a battery)

Front 185

What is the benefit of impedance matching?

Back 185

A good match between the source and load components in terms of impedancewill give the best (SNR)

Front 186

What is impedance?

Back 186

Frequency dependant resistance

Front 187

What will happen if you attache an instrument level signal to a mic pre?

Back 187

If attaching high level impedance source like a guitar to a mic pre you will get avery low level and noisy signal as the voltage is being seen mainly by the instrument.

This is because the instrument has more impedance than the mic pre (frequency dependent resistance)

A DI box should be used to lower the impedance of the instrument to match the mic pre.

Front 188

What is 'Capacitance'

Back 188

The ability of a system to store an electric charge. The ratio of the change in an electric charge in a system to the corresponding change in its electric potential.

A Capacitor is a device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator.

Also known as a 'Condenser'

Front 189

What does T R S stand for?

Back 189

Tip (Positive)

Ring (Negative)

Sleeve (Earth / Ground)

The three connecting circuits in a 1/4 inch cable that allow signal to be transferred.

Front 190

Name 4 different types of 'Jack' connector

Back 190

Mini jack / 1/8 (Headphones / 3.5mm)

1⁄4 Jack (Pro version of 1/8) Harder to unplug

Bantam / TT – Industry standard / Bigger than 3.5 and 1⁄4 Jacks

BPO (British Post Office) still in some studios for audio applications but rare

Front 191

What is electro static noise?

Back 191

Hi frequency noise that may penetrate audio connectors and enter the audio signal path.

A shield surrounding audio connectors can prevent noise from affecting audio signals.

Front 192

What is electro magnetic noise?

Back 192

This type of noise has an extremely long wavelength which can penetrate shielding and so balanced cables are used to eliminate this type of noise.

Front 193

Audio consoles have which two basic functions?

Back 193

Central routing system

Consoles provide an easy way to route signals to and from different points without re-patching.

Signal Processing

Amplification, panning and EQ are examples of signal processing found in mixing consoles.

Front 194

What is the function of a 'Bus'?

Back 194

An internal routing section enabling transport of a signal from one section (such as a channel path) of a desk to another (such as the main stereo outputs)

Front 195

What is the function of an 'Aux' or 'Auxiliary' Bus

Back 195

Used to route signals to effect units, cue mixes etc.

Front 196

What is the function of a 'Group' box

Back 196

Commonly used to collect signals from channel paths and route them to multi track inputs (recording)

Group buses are also used to route signals to effects processors during mixdown.

Front 197

What is the function of the main stereo bus?

Back 197

Used to mainly route signals from the channel or monitor paths to the main stereo mix outputs of a console.

These outputs should be connected to a two track master machine such as a DAT or HD recording device.

Front 198

On a 3 pin XLR cable what gender is the input and output?

Back 198

Input = Female

Output = Male

Front 199

What are the pin outs of an XLR cable?

Back 199

Abalanced XLR is wired as follows:

Pin 1 = Return

Pin 2 = Hot

Pin 3 = Cold

Front 200

What is Phantom Power?

Back 200

48v DC

Used to power condenser microphones.

Front 201

What type of microphone should you never use phantom power on?

Back 201

Ribbon Microphones.

Front 202

What is the function of a PAD switch?

Back 202

To lower the level of incoming signals

Front 203

What is the ø button used for on a console?

Back 203

To flip or invert the phase of a signal (180º)

Front 204

What is the difference between 'Pre' and 'Post' Aux sends

Back 204

A Post Aux send is affected by the faderposition

A Pre Aux send is unaffected by the fader position

Front 205

What is the function of the 'Insert' section of a console?

Back 205

An‘Insert Send’ contains a copy of the signal in the path where the insert isplaced. This copy may be patched to another path / device (e.g. compressor).

An ‘Insert Return’ replaces the original signal in the path where the insert isplaced with a new signal (patched in).

Front 206

Describe the function of the 'Talk Back' switch?

Back 206

Allows the communication between the engineer and themusicians.

Talkback sections generally include a built in

microphone, levelcontrol and on/off switch. 


Front 207

Name the two main types of console design?

Back 207

Split Consoles

Halfof the desk handles signals going to tape and the other half handles signalsreturning from tape.

In-Line Consoles

Each I/O module contains two completely separate paths:

ChannelPath

MonitorPath

Front 208

What is electricity?

Back 208

Electricity is the flow of moving electrons.

Front 209

What path will electrons always take?

Back 209

The path of least resistance

Front 210

True or False

An electron is negatively charged?

Back 210

True

Front 211

What is the polarity of a Neutron?

Back 211

It has no polarity as it is neutral (no charge)

Front 212

Whats is the polarity of a Proton

Back 212

Positive charge

Front 213

What is the equation for Ohms Law?

Back 213

V = I x R

(Voltage = Current multiplied by Resistance)

R = V / I

(Resistance = Voltage divided by Current)

I = V / R

(Current = Voltage Divided by Resistance)

Front 214

Describe electrical resistance

Back 214

Resistance = The amount of opposition to current flow through the medium.

The lowerthe resistance the better a conductor the material.

The higherthe resistance the better an insulator the material.

Front 215

What is electrical resistance measured in?

Back 215

Resistance is measured in Ohms Ω

Front 216

What are the positive and negative terminals on a battery known as?

Back 216

The anode (positive)

The cathode (negative)

Front 217

True or False?

Current is inversely proportional to Resistance and Directly proportional to Voltage?

Back 217

True

Front 218

Describe AC electricity (Alternating current)

Back 218

Flow of electrons periodically flips between positiveand negative much like a sine wave. An alternating current is a phase basedsystem and is used in audio as its structure is analogous to the compression /rarefaction of air particles which causes sound.

Front 219

Describe DC electricity (Direct Current)

Back 219

Implies electron flow in one direction.

You can think of DC as AC at a frequency of 0 Hz

Front 220

What is the power equation?

Back 220

P = I x V

Power = Current x Voltage

Front 221

How do you calculate the RMS level of a signal?

Back 221

1.) Square the values (S)

2.) Take the average (M)

3.) Take the square root of the average (R)

Front 222

What are semi-conductors?

Back 222

Electrical component that allows current flow only under specific conditions.

Front 223

What unit is electrical charge measured in?

Back 223

Coulombs

1 Coulomb = 6.23 x 10^18 Electrons

Front 224

What unit is electrical current measured in?

Back 224

Amperes

Front 225

What is the equation for calculating electrical charge

Back 225

Q = I x T

Charge = Current x Time

Front 226

How many joules per second are consumed by 100 Watts of power?

Back 226

100 Joules

1W = 1 joule per second

Front 227

Loudspeakers are analogous to what type of electrical component?

Back 227

A resistor

Front 228

In order, what do the four colour bands on a resistor mean?

Back 228

Band 1 = 1st digit

Band 2 = 2nd digit

Band 3 = Multiplier

Band 4 = Tolerance (+/-)

Front 229

What does Kirchoff's law state?

Back 229

In circuits wired in series voltage is shared betweenresistors while current remains the same across the entire circuit.

In circuits wired in Parallel current is shared between the resistors while voltage remains the same across the entire circuit.

Front 230

What is the equation used to calculate the

resistance in a parallel circuit

Back 230

1 / 1/R1 + 1/R2 + 1/R3 +

1/Rn + 1/ Rn etc..

Front 231

To calculate the resistance in a parallel circuit what should you put in the calculator?

Back 231

This would be for a resistance of 10 Ohms

Front 232

What is the function of a capacitor?

Back 232

Temporarily Stores Charge

If fed with AC they will block DC

Front 233

Describe the structure of a capacitor

Back 233

Capacitors consist of two metal plates separated by a non conductive material called the

'Dieletric'

Front 234

What is capacitance measured in?

Back 234

Farads

Front 235

The time is takes to charge a capacitor is determined by what equation?

Back 235

1 x t capacitor is 63% charged

3 x t capacitor is 95% charged

5 x t capacitor s 99% charged

Front 236

True or False

A high frequency AC current fed into a capacitor will result in low capacitive reactance?

Back 236

True

Front 237

True or False

A low frequency AC current fed into a capacitor will result in high capacitive reactance?

Back 237

True

Front 238

What is Impedance?

Back 238

Impedance is the overall resistance taking into account capacitive reactance and direct resistance.

Front 239

Describe an inductor

Back 239

An indictor is created when passing a current through a wire which has been coiled around.

Front 240

A current carrying conductor will induce what around itself?

Back 240

A magnetic field

Front 241

Magnetic fields are represented with what?

Back 241

Flux lines

Front 242

The number of flux lines describes what?

Back 242

Flux density

Front 243

What is Bridged Impedance Matching?

Back 243

When the load impedance is equal to or greater than 10 times the output impedance

Front 244

What will happen to the magnetic field if a conductor carries AC current?

Back 244

The magnetic field will move inwards / outwards of the conductor itself.

Front 245

What happens when an accelerating magnetic field line crosses a second parallel inductor

Back 245

EMF (Electro Magnetic Force) is generated.

Front 246

What is 'Back EMF'

Back 246

When a conductor is coiled magnetic fields will cut through the original conductor itself.

The conductor will induce EMF upon itself that will oppose its own current flow.

This is what is known as 'Back EMF'

Front 247

What is inductance measured in?

Back 247

Inductance is measured in Henry's

Front 248

What will be the 'Back EMF' produced by an inductor of 1 henry

Back 248

1Volt

Front 249

Reactance and Resistance combine into what?

Back 249

impedance (Z)

Front 250

What is the equation for calculating impedance?

Back 250

Where

Z = Impedance

R = Resistance

X = Reactance

Front 251

What kind of filter do you get if you pass output across the capacitor in a circuit that is wired containing both a capacitor and a resistor wired in series?

Back 251

Low Pass Filter

Front 252

What kind of filter do you get if you pass output across the resistor in a circuit that is wired containing both a capacitor and a resistor wired in series?

Back 252

High Pass Filter

Front 253

What is an LCR circuit?

Back 253

When a capacitor, inductor and resistor are wired in series

low frequencies will 'drop across' the capacitor

high frequencies will 'drop across' the inductor

mid frequencies will 'drop across' the resister

Front 254

Describe what the 'Cut Off' frequency of a filter is?

Back 254

The cutoff frequency of a filter is the frequency that is attenuated by -3dB

The position of a filter is given by its 'Cut Off' frequency.

Front 255

What formulae is used to calculate the cutoff frequency of a CR (capacitor resistor) filter?

Back 255

F -3dB = 1 ÷ (2π C R)

Where

F -3db = cut-off frequency

C = capacitance

R = Resistance

Front 256

What is a transformer?

Back 256

Transformers consist of two wires wound around a magnetic core.

The primary coil induces a magnetic field in the core and the core subsequently induces an (EMF) voltage in the second coil.

This way it is possible to step up or down voltage and current.

Front 257

What equation may be used to calculate voltage changes in step up / down circuits?

Back 257

V out / V in = NS / NP

NS > NP (Step up transformer)

NS < NP (Step down transformer)

Where

NS = Number of secondary coil windings

NP = Number of primary coil windings

Front 258

What is a Diode?

Back 258

A diode is semi conductor device that normally only allows current to travel in one direction

Front 259

What are the three general guidance values used for Impedance matching?

Back 259

Low impedance = Less than 600 Ω

Medium impedance = 600 Ω - 10 kΩ

High impedance = More than 10 kΩ

Front 260

What do DI (Direct Injection) boxes do to the

impedance of a device?

Back 260

They lower it.

Front 261

What is the main component of a DI box?

Back 261

The Transformer

Front 262

What is an 'Active' DI box?

Back 262

This type of DI box is able to match impedance without the use of a transformer to step down voltage.

Front 263

What electrical function is performed by a

microphone?

Back 263

A microphone is an electroacoustic Transducer

Front 264

What are the main characteristics of a dynamic microphone?

Back 264

Requires large SPL to begin transduction

Slow transient response

Less sensitive to smaller variations in SPL

Limited High Frequency response

Resilient (Can withstand high SPL)

Less transparent (colour sound)

Muddier in mid frequencies

Effective when placed close to sound source

Front 265

What is a 'Humbucking' coil?

Back 265

Eliminates Hum (Noise) by means of common mode rejection similar to the principles behind balanced cables.

Front 266

What are the main characteristics of a

Ribbon Microphone

Back 266

Fragile construction (Ribbon made of aluminium)

Fast transient response

Low impedance (requires transformer)

Sensitive to wind

Fast directional microphone (bi directional)

Prone to proximity effect

Front 267

Describe the principle of directionality

Back 267

Directionality is a measure of the microphones sensitivity to sound relative to the direction or angle from which it arrives

Front 268

What is a 'Polar pattern' ?

Back 268

A polar pattern is a graph plotting the variation of sensitivity in 360 degrees of a given microphone.

0 degrees represents the front of the Mic.

Front 269

What are the main characteristics of a

condenser microphone?

Back 269

Low output (an internal amplifier is usually part of the microphone design)

Very fast transient response times

Highly sensitive with an extended HF response

Should be placed further away from sound sources.

Prone to feedback in live applications

Front 270

What is compansion?

Back 270

A combination of compression / expansion used to return a compressed signal to its original

dynamic range.

Used in noise reduction.

Front 271

What is ducking?

Back 271

Inverts the function of a gate so the gate stays open when signals drop below the threshold. Used with a key input (classically a mic input used in radio broadcasts)

Front 272

Describe the function of a 'Transistor'

Back 272

Transistors are semi-conductors used commonly for current amplification and control, and

as switches.

Front 273

What material are most modern day microphone diaphragms made of?

Back 273

Mylar (a very elastic plastic)

Front 274

What is the frequency range boost of a dynamic microphone that is caused by mechanical resonance?

Back 274

300 Hz

Front 275

In order to avoid inherent phase cancellation issues which to microphone types should not be used at the same distance from the sound source?

Back 275

Dynamic & condenser mics

Front 276

What type of waveform cannot be reproduced by a dynamic microphone

Back 276

A Square wave

A dynamic microphone cannot reproduce a square wave because it generates voltagebased on diaphragm movement (i.e. produces no output voltage when static).

Front 277

What is a SDC?

List some of its characteristics

Back 277

Small Diaphragm Condenser

Front load

Better at high SPL (less sensitive)

Greater dynamic range

Greater frequency

Higher self noise

Front 278

What is a LDC

List some of its characteristics

Back 278

Large Diaphragm Condenser

Opposite of a SDC as well as:

More colour

Less transparent

Lower self noise

Front 279

Name the 5 main 'Polar Patterns'

Back 279

Cardioid

Figure of 8 (Bi directional)

Hyper Cardioid

Super Cardioid

Omni Directional

Front 280

Which microphone 'polar pattern' does not exhibit the proximity effect.

Back 280

Omni Directional microphones

Front 281

How much time should you leave a valve microphone to both warm up and cool down.?

Back 281

1 hour to warm up.

10 minutes to cool down.

Front 282

What should you always use with a ribbon

microphone?

Back 282

A pop shield

Front 283

What type of music are Small Condenser Microphones almost always used to record?

Back 283

Classical music.

An SDC is very transparent which is ideal for

classical music.

Front 284

What unit is microphone sensitivity usually measured in

Back 284

Microphone sensitivity values may be expressed in miliVolts per Pascals or as a dB value

referenced to 1 volt per Pascal.

Front 285

What is 'self noise' ?

Back 285

This is the noise produced by amicrophone’s circuitry and design.

Self-noise is usually described in decibels with a weighting curve applied.

Front 286

What is the difference between a 'Pure pressure microphone' and a 'pressure gradient microphone'

Back 286

In a pure pressure microphone only pressure matters, sound only reaches one side of the mic.

In a pressure gradient microphones it only matters that there is adifference between front and back of the diaphragm

Front 287

What are the latin terms for the auditory ossicles?

Back 287

Malleus (Hammer)

Incus (Anvil)

Stapes (Stirrup)

Front 288

What is the 0 dBu voltage for Broadcast equipment?

Back 288

+8 dBu

1.95 Volts

Front 289

What is the standard dBu level and voltage for Broadcast equipment?

Back 289

+8 dBu

1.95 Volts

Front 290

What is the standard dBu level and voltage for

Professional equipment

Back 290

+4 dBu

1.228 Volts

Front 291

What is the dBu level for Hi-Fi equipment

Back 291

-10dBu

0.245 Volts

Front 292

What is the standard level for dBu and voltage on Semi-Pro Equipment?

Back 292

-10 dBV

0.225 Volts

Front 293

What is the standard level for dBu and voltage on Semi-Pro Equipment?

Back 293

-10 dBV

0.316 Volts

Front 294

What do the 4 bands on a resistor denote?

Back 294

Band 1 = 1st digit

Band 2 = 2nd digit

Band 3 = Multiplier

Band 4 = Tolerance

Front 295

What are the resistor band colour codes?

Back 295

Front 296

List the main components of a loudspeaker?

Back 296

Front 297

What is loudspeaker cone compliance?

Back 297

High compliance = easy to move the cone

Low compliance = difficult to move the cone

Front 298

What is the loudspeaker damping factor?

Back 298

he amplifier’s ability to control the loudspeaker (excursions)

Front 299

What is the frequency of concert pitch?

Back 299

A4 = 440 hZ

Front 300

What is the frequency of C5?

Review frequency chart for the audio spectrum

Back 300

C5 = 523.5 Hz

Front 301

What is the frequency of middle C?

Back 301

261.62 Hz

Front 302

True or false

If you add multiple logarithms with the same base you can multiply the arguments

Back 302

True

Front 303

True or false

If you are multiplying the same base you can add the exponents

Back 303

True