Sound1.01 and
Environmental Noise
Presented to the Young RMLA by
Siiri Wilkening
On the menu
Sound 1.01
NZ NoiseStandards
Road Traffic Noise
Construction Noise
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Physics of sound
Sound is a pressure
fluctuation, travelling in waves
Valve rotation = 100 /sec
Frequency of Sound = 100 Hz
Loudspeaker
Sound can vary in
frequency (pitch)
and level (magnitude)
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Frequency & wavelength
Frequency & wavelength of everyday sound
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Frequency weighting
“A” weighting:
Response of the
human ear
Commonly used for
industrial and
environmental noise
assessment
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Sound Level – The decibel (dB) scale
Pressure Scale is
Impractical
Decibel scale chosen
for convenience
Hearing response is
logarithmic rather than
linear
Lawnmower (85 dB) +
Lawnmower (85 dB) =
88 dB
Typical sound pressure levels
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Changes in Noise Level
Change in
Sound Level (dB)
Subjective Reaction
Impact / RMA Effect
1-2
Insignificant change
Negligible/less than minor
3-4
Perceptible change
Slight/Minor
5-8
Appreciable change
Moderate
9 - 11
Halving/doubling of loudness
Significant/Substantial
> 11
More than a halving/doubling
Serious/Severe
of loudness
Sound level (dB)
Statistical Analysis
80
75
LAmax
LA10
70
LAeq
65
LA90
60
55
50
Time
• LAmax
maximum noise level
• LA10
level exceeded for 10% of the time
• LAeq
average noise level
• LA90
level exceeded for 90% of the time
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Common Misconceptions
“Trees act as an acoustic barrier” –
No! Need at least 100m of dense bush for 3 dB
reduction
“Putting eggboxes on the walls of my band room
means I can play as loud as I like”
No! Too light to insulate against noise.
“Sound travels upwards”
No! Sound travels in all directions.
Overview of NZS 68xx Series
6801: Measurement & Definitions
6802: Assessment (General Sources)
6803: Construction Noise
6805: Airport Noise
6806: Road Traffic Noise
6807: Helicopter Noise
6808: Wind Turbine Noise
6809: Port Noise
NZS 6806:2010
“Acoustics – Road-traffic noise –
New and altered road”
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Basic Considerations
Virtually everyone contributes and is
affected
Not entirely controllable
Flexibility and pragmatism
Based on RMA, specifically BPO
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Limitations
Applies only if project has (some)
adverse effect
Minimum performance for mitigation
Defined assessment area
(100/200 m from road)
Maintenance excluded (e.g. resurfacing)
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Noise Criteria Categories
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Criteria (all LAeq(24h))
Category A - Primary, external
• 57 dB new roads / 64 dB altered roads
Category B – Secondary, external
• 64 dB new roads / 67 dB altered roads
Category C – Backstop, internal
• 40 dB (if internal level would be 45 dB or more)
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Mitigation Options
Structural Mitigation:
• Road surface
• Barriers or bunds (or tunnels)
Building Modification Mitigation
• Ventilation
• Insulation
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Noise Barriers
Effectiveness: length and
height
Close to source or receiver
Break acoustic line-of-sight
Barrier material 10 -15 kg/m2
• 17 mm ply
• 9 mm fibre cement
• 20 mm timber board and batten
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NZS 6806: BPO Assessment
Iterative process
Input from entire Project Team
Advantage:
robust and practicable mitigation
Implications:
Time!!! and potential confusion
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Main Issues
Criteria:
Category C (internal) perceived “better” than
Categories A and B (external)
Uncertainty:
no definitive “limit”
(Note: condition formulation)
Inclusion of cost:
It’s a dirty word!
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NZS 6803:1999
“Acoustics- Construction Noise”
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Basic Considerations
Construction activities are:
• Noisier than normal activities
• Of limited/finite duration
• Necessary to progress society
Need to find balance between
• Amenity of residents/affected parties
• Necessity of works
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Recommended Criteria
Residential:
• Day
• Night
75 dB LAeq / 90 dB LAmax
45 dB LAeq / 75 dB LAmax
Business:
• Day
• Night
75 dB LAeq
80 dB LAeq
Can be adjusted for
• Duration
• Ambient noise levels
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Construction Noise Management
Construction Noise and Vibration
Management Plan — CNVMP
Site Specific Construction
Noise/Vibration Management Plans
SSCNMPs/SSCVMPs
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Construction Mitigation
Monitoring
Temporary/permanent barriers
Shielding of individual items of
equipment
Selection of equipment
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Construction Mitigation - continued
Noise sensitive activities, e.g. schools,
hospitals: timing
Consultation/Communication
Miscellaneous:
reversing alarms, unsecured tail gates,
radios, horns, shouting
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Offices
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Hamilton (1)
Shanghai (2)
Hong Kong (1)
Ireland (2)
Great Britain (2)
France (1)
Melbourne (24)
Sydney (4)
Adelaide (2)
Perth (2)
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2013 Group Conference
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