Noise Pollution Flashcards
Differentiate acoustic waves fr sound waves
We can’t hear all acoustic waves, but we can hear all sound waves.
Differentiate sound from noise.
Not all sounds are noises.
noise = Unwanted sound or sound that is loud, unpleasant or unexpected; disagreeable or undesired sound
non-steady noise vs impulsive noise. What is the difference?
time duration
identify type of noise: Noise with negligibly small fluctuations of sound pressure level within the period of observation. A. steady noise B. fluctuating noise C. intermittent noise D. impulsive noise
A
Which are the subtypes of non-steady noise? Differentiate the two. A. steady noise B. fluctuating noise C. intermittent noise D. impulsive noise
B and C
B.Fluctuating Noise - variations are always above the background noise
C.Intermittent Noise - variations sometimes go below the background noise
noise for which the level changes continuously and to a great extent during the period of observation A. steady noise B. fluctuating noise C. intermittent noise D. impulsive noise
B
Consists of one or more bursts of sound energy, each of a duration less than about 1 second. A. steady noise B. fluctuating noise C. intermittent noise D. impulsive noise
D
Classify noise accdg to source. A. peeling of fruits B. automobiles C. generator sets D. hospitals
A. domestic
B. commercial
C. industrial
D. commercial
commercial: goods, services DELIVERY
industrial: PRODUCTION
Frequency where human hearing is most sensitive @ hearing
500-6000 Hz
but humans can hear from 20-20,000 Hz
Enumerate 3 things to consider in sound measurement
- Frequency content of the sounds (higher frequency,
more harmful to humans) - Overall sound pressure levels
- Variations of these levels with respect to time.
False about sound pressure
A.raw measurements xpressed in terms of decibels
B.measured on a logarithmic scale
C.measure of vibrations in the air which make up sound
A
Expressed in terms of a datum pressure corresponding to the lowest sound pressure which the young normal ear can detect, now called the sound pressure level, Lp (or SPL).
main purpose of sound weighting
to determine the relative strengths of frequency components making up a particular environmental noise.
Which sound weighting technique is the most common? A. A-Weighting B. B-Weighting C. C-Linear Frequency Weighting D. D-Linear Frequency Weighting
A
False about A-Weighting
A. Weights high frequencies as less important than mid-
and low-range frequencies.
B. Tries to approximate the frequency response of our
hearing system.
C. Prioritize certain frequencies
A
low frequencies - less priority
False about C- Frequency Weighting
A. Used to determine a time-integrated “peak” level with a time constant of no more than 0.05 ms.
B. used if the actual instantaneous pressure cannot be determined
C. for consistently soft noises
C
loud dapat
Pain threshold for noise – approx. __
give a range!
120-130 dB
Maximum of ___ -
acceptable for occupational noise in PH
Give value & frequency
90 dB (for 8 hrs/day or 40 hrs/week) i
differentiate fast-response from slow-response measuring instrument for noise
Fast-response – time constant of 0.125 s; intended to approximate the time constant of the human hearing system.
Slow-response – time constant of 1 second; intended to make it easier to obtain an approximate average value of fluctuating levels from simple meter readings.
Constant noise → __
Varying noise levels → __
(Slow-response, Fast-response)
Constant noise → Fast-response
Varying noise levels → Slow-response
Measuring instruments for noise are placed where?
nearest people, at the ear level.
sound level meters: laboratory reference standard A.Type 0 B.Type 1 C.Type 2 D.Type 3
A
sound level meters: general field application A.Type 0 B.Type 1 C.Type 2 D.Type 3
C
sound level meters: field noise survey A.Type 0 B.Type 1 C.Type 2 D.Type 3
D
Which does not increase because of noise? A. respiratory rate B. metabolic rate C. pupillary size D. number of RBCs
D
Which is not a non-auditory health effect of noise pollution? A.nervous pain B.buzzing in the ears C.somnolence D.Stress induced gastritis
C
sleeplessness dapat
identify: temporary loss of hearing after going from loud place to a quiet one
Transient threshold shift
As age increases, ability to hear decreases. what is this called?
presbycusis
differentiate reactive from dissipative muffler
reactive - low freq/small exhausts
dissipative - high frew/large exhausts
what is reverberation control?
Addition of sound absorbing material to reverberant
spaces to reduce reflected noise fields
differentiate emission from immersion
Emission – generation
Immision – injection or addition
Which area requires quietness (i.e. hospital)? A. AA B. A C. B D. C E. D
A
Which area is for residential purposes? A. AA B. A C. B D. C E. D
B
Which area is a light industrial area? A. AA B. A C. B D. C E. D
D
In eng'g measures to control noise, give one example of: A. source modification B. transmission reduction C. passive protection D. traffic management
A - low noise road surface, changing engine
B - enclosures around machinery, noise screen
C - ear muffs, insulation of dwelling
D - speed limit, electronic guidance of traffic flow
