Decibels

Question 1

dBm Reference

Answer 1

1mW

Question 2

dBm=

Answer 2

dBm=10LogP/.001

Question 3

dBu Reference

Answer 3

.775V

Question 4

dBu=

Answer 4

dBu=20LogE/.775

Question 5

dBV Reference

Answer 5

1V

Question 6

dBV=

Answer 6

dBV=20LogE/1

Question 7

Threshold of Hearing, Feeling, & Pain

Answer 7

Hearing: 0dBSPL

Feeling: 118 dBSPL

Pain: 140 dBSPL

Question 8

2x Power=

Answer 8

3dB

Question 9

2x SPL=

Answer 9

6dB

Question 10

2x Voltage=

Answer 10

6dB

Question 11

10x SPL=

Answer 11

“Twice” as Loud

Question 12

0 VU= ? for Pro Audio

Answer 12

0VU= 1.23V for +4dBm (Pro Audio)

Question 13

0 VU= ? for Broadcasting Equipment

Answer 13

0 VU= 1.09V for +8dBm (Broadcasting)

Question 14

0 VU= ? for Consumer Audio

Answer 14

0 VU= .316V for -10dBV (Consumer)

Question 15

A dBm meter is only accurate across ____Ω

Answer 15

600Ω

Question 16

Level Changes:

1) 2x Power
2) 2x Voltage
3) 10x Increase in Sound

Answer 16

1) dB=10Log P₁/P₂
2) db=10Log E₁/E₂
3) dB=20Log SPL₁/ SPL₂

Question 17

Each Doubling in Distance There Is a ____dB Decrease in Level

Answer 17

6dB

(dB=20Log d₁/ d₂)

Question 18

Doubling Distance Sound Will Radiate by ____times

Answer 18

4

(4πr²)

Question 19

Voltmeter

Answer 19

Will show relative volume or loudness
Divided into Volume Units

A voltmeter of a specified transient response

Question 20

Full Scale Meter
Peak Program Meter

Answer 20

Calibrated in dBFS
Does not correlate with percived volume

Question 21

Near Field

Answer 21

An area in the immediate vicinity of the transducer

Question 22

Far Field

Answer 22

Area just beyond the near field

Question 23

Free Field

Answer 23

Where the inverse square law applies

Question 24

Reverberant Field

Answer 24

When the contribution of the sound source is not the strongest

Question 25

Echo

Answer 25

The delayed arrival of a reflected sound

Question 26

Flutter Echo

Answer 26

Short rapid succession of echos
Created by parallel walls or diagonally opposite corners

Question 27

Reverberation

Answer 27

A series of multiple echoes so closely spaced to merge into a continuous sound, decreasing in amplitude over time

Question 28

Reverberation Time

Answer 28

The time it take the original steady state sound to decay 60 dB @ 500 Hz