Acoustics

Question 1

Sound

Answer 1

audible emissions resulting from the vibration of molecules within an elastic medium. It is generated by either a vibrating surface or the movement of a fluid.

Question 2

Noise

Answer 2

Unwanted Sound

Question 3

Frequency

Answer 3

cycles per second (Hz)

Question 4

Period

Answer 4

seconds per cycle

Question 5

Wavelength

Answer 5

distance per cycle

Question 6

rarefactions

Answer 6

expansions in the movement of air from sound waves

Question 7

What kind of wave does sound form?

Answer 7

Sine

Question 8

Broadband

Answer 8

Sounds composed of several frequencies and amplitudes at the same time

Question 9

Pure Tone

Answer 9

Sound at a single frequency

Question 10

Sound Power on a lightbulb is similar to

Answer 10

Bulb Wattage

Question 11

Sound Pressure on a lightbulb is similar to

Answer 11

Brightness

Question 12

Pin drop dB

Answer 12

10

Question 13

Whisper dB

Answer 13

30

Question 14

Quiet Conversation dB

Answer 14

40

Question 15

Average Office dB

Answer 15

50

Question 16

Normal Speech dB

Answer 16

60

Question 17

Factory dB

Answer 17

80

Question 18

Centrifugal Chiller dB

Answer 18

70 - 95

Question 19

Car Horn dB

Answer 19

110

Question 20

Pain Threshold dB

Answer 20

130

Question 21

Fighter Jet Launch dB

Answer 21

150

Question 22

Adding two sources of same dB level =

Answer 22

3 dB increase

Question 23

splitting a source 50/50 reduced sound power by

Answer 23

3 dB

Question 24

______ increase is twice the energy but we barely notice the difference in loudness

Answer 24

3 dB

Question 25

doubling receiver distance (free field) from source reduces sound level by

Answer 25

6 dB

Question 26

_____ increase is perceived as being twice as loud

Answer 26

10 dB

Question 27

What is A-Weighting used for (application)?

Answer 27

- sound in outdoor environments - local sound ordinances - OSHA (hearing protection)

Question 28

Noise criteria uses how many descriptors?

Answer 28

1

Question 29

What sound is made when there is a high quantity of low-frequency sound?

Answer 29

Rumble

Question 30

What sound is made when there is a hig quantity of high-frequency sound?

Answer 30

Hiss

Question 31

A source generates

Answer 31

sound power

Question 32

What is a path?

Answer 32

ways sound travels from the source

Question 33

What is a Receiver?

Answer 33

Person in used space

Question 34

What are sources of Sound made by Trane?

Answer 34

- compressors - fans - valves - dampers - water turbulence - air turbulence

Question 35

What are the three types of sound paths?

Answer 35

- airborne - breakout - transmission

Question 36

What is attenuation?

Answer 36

the reduction in sound level as sound travels along a path from source to receiver

Question 37

What is regeneration?

Answer 37

an increase in sound level caused by turbulence in the air stream

Question 38

Typical range for Room Effect?

Answer 38

-5 to -15 dB (always negative)

Question 39

Soft rooms have what kind of room effect?

Answer 39

high effect

Question 40

if a compliant, _______ dB quieter needed BELOW original target to appease customer

Answer 40

5-7