Noise

Question 1

Socioacusis

Answer 1

Permanent hearing loss from environmental noise

Question 2

Presbycusis

Answer 2

Hearing loss from aging

Question 3

How many ft/sec does sound travel through air at OF, sea level

Answer 3

1128 feet per second (770 miles per hour)

Question 4

How many feet per second does sound travel in water

Answer 4

4700 feet per second

Question 5

What frequency range can the human ear hear

Answer 5

20 to 20,000 Hertz

Question 6

What is a decibel (dB)

Answer 6

The ratio of the level of sound in question compared to the smallest sound distinguishable to the human ear.

Question 7

How many dB in the following noises:

Whisper
Human conversation
Vacuum Cleaner
Semi Truck
Jet engine at take off

Answer 7

Whisper - 5
Human conversation - 40
Vacuum Cleaner - 60
Semi Truck - 80
Jet engine at take off - 140

Question 8

Permissible Exposure Limit (PEL) for noise

Answer 8

85 dB @ 8 hours

Question 9

3 devices used to measure noise

Answer 9

Sound level meters
Octave level analyzer
Noise dosimeter

Question 10

Sound Level Meters

Answer 10

Converts pressure waves in the air to an electronic signal and displays the SPL (sound pressure level)

Question 11

Octave Level Analyzer

Answer 11

Used to test human hearing by emitting different frequency sound waves

Question 12

Noise Dosimeter

Answer 12

Consists of a sound meter, integrator and indicator. Worn by an employee to measure sound exposure over a work shift

Question 13

What is TTS

Answer 13

Temporary Threshold Shifts. Hearing losses which are recoverable after a period of time. The body usually gives warning signals such as tinnitus (ringing in ears)

Question 14

Permanent Threshold Shifts

Answer 14

Permanent loss of hearing from daily exposure over a long period

Question 15

Baffles

Answer 15

are designed to impede or alter the direction of noise, thus reducing the noise. Common at shooting ranges and freeways.

Question 16

What is SPL

Answer 16

Sound Pressure Level. A logarithmic measure of the effective pressure of a sound relative to a reference value. Sound pressure level, denoted Lp and measured in dB, is defined by.

Frequency and Duration

Question 17

Doubling of sound pressures results in an increase of ___ dB

Answer 17

3 dB (e.g. two 100dB speakers would make 103dB)

Sound does not have an additive effect

Question 18

Definition of noise

Answer 18

“unwanted sound”

Question 19

Inverse Square Law

Answer 19

Doubling of distance from a noise source results in a reduction of -6 dB

Question 20

Leq

Answer 20

Equivalent continuous sound level. expresses the sound energy average over a period of time

Question 21

Continuous sound
intermittent Sounds
Impulsive Sounds

Answer 21

Continuous - vary little over a period of time
intermittent - Emitted throughout relatively quiet periods
Impulsive - High Sound levels with very short durations

Question 22

The statistical Model

Answer 22

uses statistics to describe the noise environment. Noise levels are sampled at a constant interval.

Question 23

LDN

Answer 23

Day-Night average sound level

Question 24

Sound insulation

Answer 24

use of structures and materials to reduce transmission of sound

Question 25

Sound transmission class

Answer 25

STC - a rating system to sound insulation properties of partitions such as walls, floor, ceilings

Question 26

STL

Answer 26

Sound transmission loss - measure of sound insulation provided by a structural configuration

Question 27

Sound-absorption coefficient

Answer 27

Ability of a surface to absorb sound

Question 28

NRC

Answer 28

Noise reduction coefficient - is a scalar representation of the amount of sound energy absorbed upon striking a particular surface

Question 29

What is the MOST common type of noise measurement device used for initial inspections?

Answer 29

Sound Level Meter