Noise and Skateparks
The #1 request
we get is for noise studies but noise complaints are rare after
the skatepark is built. In fact I have only heard of one city
that had a noise problem and that was Brea CA. They built their
park at the base of a hill and the noise traveled upward to the
homes on the top of the hill.
To test the different surfaces we used a digital sound level meter.
Weighting set at C and response at fast.
And took readings:
Ambient reading approx. 100 feet from the park
At the park entrance
Inside the park at the ramps, mini ramp or bowl.
Noise levels
were measured in decibels and we recorded the lowest and highest
readings.
The lowest reading would be when no one was riding the ramp in
front of the meter. For some parks it could be lower than the
ambient reading. The Santa Monica skatepark is below ground so
when you are "in" the park there is little if any traffic noise.
*Phenolic Fiber Laminate - a recommended man-made surface
* a busy street is approx. 80dB
Concrete
in-ground park
Test park Santa Monica Skatepark approx 18,000 sq feet
50 participants
in the park at time of test
Location dB
Low Reading dB
High Reading
Ambient noise
64
72
30 feet from entrance 65
70
at the entrance 66
74
inside park 63
76
at the bowl 64
78
flatland slide near entrance
*This is an old school maneuverwhere the rider skids sideways
on his/her board making sound similar to fingernails on a blackboard.
80
Wood Frame
Mini Ramp
skatelite over 2 ¾ inch layers of plywood Test Park SPA mini ramp
12 riders but only 1 person riding at a time
Ambient noise 75
78
On Ramp 77
85
Steel Frame
Phenolic Fiber Laminate over ½ inch man made base Test
park Hollenbeck, East Los Angeles, the park is on a hill, surrounding
homes are on lower ground Park is 12,000 sq feet and there were
10 skaters using the park
Ambient noise 77
80
150 feet from
the park 70 73
50 feet from the park 68
73
20 feet from the park 74
78
inside the park 80
87
Steel Frame
w Phenolic Fiber Laminate attached directly to the frame
Test Park Rogers Park in Inglewood
7 skaters in the park
Ambient noise 72
76
At 150 feet 76
85
At 50 feet 78
89
At entrance to park
78 89
Inside the park 82
89
Steel Frame
w Steel Surface
Test Park Papa Jack's Malibu 17 skaters in the park
Ambient noise 71
78
Entrance to park 78
80
Inside park 80
96
Portable
Ramps
Fiberglass
ramps
Ambient noise 75
78
Ramp noise 84
89
Man-made
Surface w Steel Frame
Ambient noise 75
78
At the ramp
88
90
Concrete had
the lowest noise levels and steel the highest but at 100 feet
from the park there was little noise above the surrounding ambient
noise no matter what surface. Cities worry a lot about how the
noise will affect the neighbors but we might need to look at how
it will affect the users. According to the National Institute
for Occupational Safety and Health (1998), the maximum exposure
time at 85 dBA is 8 hours. Most skateparks will fall into that
range with the exception of the steel surfaces we tested. Some
of the builders are using a heavier gauge steel surface with powder-coating.
I was not able to find one of the new steel surfaces to test.
The surface we tested had no coating.
Excerpt from
www.asha.org/public/hearing/disorders/noise.htm
Noise Levels
Both the amount
of noise and the length of time you are exposed to the noise determine
its ability to damage your hearing. Noise levels are measured
in decibels (dB). The higher the decibel level, the louder the
noise. Sounds louder than 80 decibels are considered potentially
hazardous. The noise chart below gives an idea of average decibel
levels for everyday sounds around you.
Painful:
150 dB = rock
music peak
140 dB = firearms,
air raid siren, jet engine
130 dB = jackhammer
120 dB = jet
plane take-off, amplified rock music at 4-6 ft., car stereo, band
practice
Extremely
loud:
110 dB = rock
music, model airplane
106 dB = timpani
and bass drum rolls
100 dB = snowmobile,
chain saw, pneumatic drill
90 dB = lawnmower,
shop tools, truck traffic, subway
Very loud:
80 dB = alarm
clock, busy street
70 dB = busy
traffic, vacuum cleaner
60 dB = conversation,
dishwasher
Moderate:
50 dB = moderate
rainfall
40 dB = quiet
room
Faint:
30 dB = whisper,
quiet library
Warning
Signs of Hazardous Noise
• You
must raise your voice to be heard
• You can't hear someone two feet away from you
• Speech around you sounds muffled or dull after leaving
a noise area
• You have pain or ringing on your ears (tinnitus) after
exposure to noise.
Hazardous
Noise
Sounds louder
than 80 decibels are considered potentially dangerous. Both the
amount of noise and the length of time of exposure determine the
amount of damage. Hair cells of the inner ear and the hearing
nerve can be damaged by an intense brief impulse, like an explosion,
or by continuous and/or repeated exposure to noise.
Examples of
noise levels considered dangerous by experts are a lawnmower,
a rock concert, firearms, firecrackers, headset listening systems,
motorcycles, tractors, household appliances (garbage disposals,
blenders, food processors/choppers, etc.) and noisy toys. All
can deliver sound over 90 decibels and some up to 140 decibels.
| Approximate
Decibel Level |
Examples
|
| •
0 dB |
the
quietest sound you can hear. |
| •
30 dB |
whisper,
quiet library. |
| •
60 dB |
normal
conversation, sewing machine, typewriter. |
| •
90 dB |
lawnmower,
shop tools, truck traffic; 8 hours per day is the maximum
exposure (protects 90% of people). |
| •
100 dB |
chainsaw,
pneumatic drill, snowmobile; 2 hours per day is the maximum
exposure without protection. |
| •
115 dB |
sandblasting,
loud rock concert, auto horn; 15 minutes per day is the maximum
exposure without protection. |
| •
140 dB |
gun
muzzle blast, jet engine; noise causes pain and even brief
exposure injures unprotected ears; maximum allowed noise with
hearing protector. |
www.american-hearing.org/name/noise_induced.html#intensity
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