dB

Question 1

What is a decibel?

Answer 1

1/10th of a Bel A dimentionless unit used to describe a ratio of either power or pressure; needs two values to have meaning

Question 2

When a sound is louder, how does it affect the frequencies?

Answer 2

As sound gets louder the frequency response becomes more linear—you perceive all frequencies more evenly rather than perceiving some frequencies as being louder than others

Question 3

How much is 0dB in Pa?

Answer 3

0.00002 Pa

Question 4

If there is a doubling of power (Watts) what is the rule?

Answer 4

+3 dB m

Question 5

If there is a halving of power (Watts), what is the rule?

Answer 5

-3 dB m

Question 6

If there is a doubling in pressure (SPL), what is the rule?

Answer 6

+6 dB SPL

Question 7

If there is a halving in pressure (SPL), what is the rule?

Answer 7

-6dB SPL

Question 8

If there is a tenfold increase in power (Watts), what is the rule?

Answer 8

+10 dB m

Question 9

If there is a tenfold decrease in power (Watts), what is the rule?

Answer 9

-10 dB m

Question 10

If there is a tenfold increase in pressure (SPL), what is the rule?

Answer 10

+20 dB SPL

Question 11

If there is a tenfold increase in pressure (SPL), what is the rule?

Answer 11

-20 dB SPL

Question 12

What is the quantifier for Watts re: decibels?

Answer 12

dB m

Question 13

What is the quantifier for pressure re: decibels?

Answer 13

dB SPL

Question 14

Formula for determining ratio for power

Answer 14

dB m = 10 x log (p1/p2)

Question 15

Formula for determining ratio for sound pressure

Answer 15

dB SPL = 20 x log (e1/e2)

Question 16

DEF: Sound Pressure Level (SPL)

Answer 16

local pressure deviation from the ambient (average, or equilibrium) atmospheric pressure, caused by a sound wave

Question 17

What is the standard international (SI) unit for sound pressure?

Answer 17

Pascal (Pa)

Question 18

If only one value is given when determining dB ratio, what is the assumed other value?

Answer 18

0 dB

Question 19

What type of scale is dB?

Answer 19

logarithmic

Question 20

DEF: phon

Answer 20

a unit of loudness measurement for pure tones

Question 21

DEF: masking

Answer 21

when a sound is covered up by another, louder/more harmonically rich sound in the same frequency range

Question 22

Why do sound waves travel faster in warmer temperatures?

Answer 22

The air molecules have more energy at a higher temperature and vibrate faster enabling sound waves to travel more quickly

Question 23

What is a longitudinal wave?

Answer 23

A wave in which the displacements of a medium are in the direction of or directly opposite to the direction of prolongation of the wave

Question 24

What is a transverse wave?

Answer 24

A wave where the displacements of a medium are at a right angle to the direction of propagation of a wave

Question 25

what does the "m" in dBm stand for?

Answer 25

milliwatts

Question 26

what is the equivalent to 0dBm in watts?

Answer 26

0.001 watts (1 milliwatt)

Question 27

P = V^2 / R

Answer 27

R = resistance in ohms V= voltage in volts P= electric power in watts

Question 28

What equation do you use when calculating the value in dBu against a given reference in watts ?

Answer 28

pressure dBu = 20 x log (p1/p2)

Question 29

What equation do you use when calculating the value in dBV against a given reference in volts ?

Answer 29

pressure dBu = 20 x log (p1/p2)

Question 30

What equation do you use when calculating the value in dBm against a given reference in volts ?

Answer 30

power dBm = 10 x log (e1/e2)

Question 31

What are weighting networks?

Answer 31

Ways of measuring decibels which account for the Fletcher Munsen curve.

Question 32

A Freq. Weighting (incl. Phon line reference) dB_A

Answer 32

weighting network designed to reflect the response of human hearing, generally shown in dB(A). Has the most dramatic frequency response referenced to the 40 Phon line used between 20-55 dB SPL

Question 33

B Freq. Weighting (incl. Phon line reference) dB_B

Answer 33

Used to weight things of moderate volume referenced to the 70 Phon line used between 55-85 dB SPL

Question 34

C Freq. Weighting (incl. Phon line reference) dB_C

Answer 34

used for louder volumes, above 80 dB referenced to the 100 Phon line used about 85 dB SPL

Question 35

DEF: dBW

Answer 35

The decibel watt or dBW is a unit for the measurement of the strength of a signal expressed in decibels relative to one watt.

Question 36

What is the formula for power in dBW?

Answer 36

Question 37

DEF: dBm

Answer 37

is unit of level used to indicate that a power ratio is expressed in decibels (dB) with reference to one milliwatt(mW)

Question 38

What is the formula for dBm?

Answer 38

Question 39

0dBu reference level in V?

Answer 39

0.775 V

Question 40

What is the reference level for 0dBV in volts?

Answer 40

0dBV = 1 volt

Question 41

Nominal operating level for professional standard equipment?

Answer 41

+4 dBu 1.2 V

Question 42

Nominal operating level for consumer/semi-pro grade equipment?

Answer 42

- 10 dBV 0. 32 V

Question 43

how do you calculate the voltage based on the reference value?

Answer 43

10^(dB/20)x [0dB value]

Question 44

What is the voltage for professional grade equipment (+4dBu) in v rms?

Answer 44

1.228 v rms 10^(4/20) x 0.775 = 1.228 v rms

Question 45

What is the voltage for consumer grade equipment (-10 dBV) in v rms?

Answer 45

0.316 v rms 10^(-10/20) x 1 =0.316 v rms

Question 46

0 dBm in watts?

Answer 46

0.001 W (1 mW)

Question 47

How do decibels change with distance?

Answer 47

The sound intensity level decreases by half (of the initial value of sound intensity, -3dB) with doubling of distance.

Question 48

Standard operating levels for hi-fi equipment?

Answer 48

- 10 dBu 0. 25 V

Question 49

What is the standard operating level for broadcasting?

Answer 49

6-8 dBu 1.55 V - 1.95 V

Question 50

DEF: dBV

Answer 50

a logarithmic voltage ratio with a reference to voltage of 1V

Question 51

DEF: dBu

Answer 51

a logarithmic voltage ratio with a reference of 0.775 volts

Question 52

DEF: dBFS

Answer 52

a unit of measurement for digital systems using a binary code where 0dBFS is assigned to the maximum possible digital level

Question 53

What is the difference (in dB) between the semi-pro/consumer standard level (-10dB) and the professional standard level (+4dB)?

Answer 53

11.76 dB