Types of Community
The following paragraphs discuss
some of the sources of community noises, with particular reference to the Hong Kong
The day-time ambient sound
pressure levels measured in rural and urban areas in Hong Kong are shown in Figure B4.
These values are the minimum levels at the locations shown. The levels for rural areas, 44
to 55 dB(A), indicate the lowest level which exist in Hong Kong. Regrettably, the levels
in housing estates are high. Depending on the location, the difference between rural and
urban areas shown can be 10 to 20 dB(A).
Figure B4 Some Daytime Ambient Noise in HK
Construction noise in Hong Kong
comes from a number of sources, notably the pile driver, pneumatic drill, air compressor,
concrete mixer and other diesel power construction machinery. Although the area affected
by piling noise is far less than that of aircraft, the hazardous effect sometimes could be
higher. This is because of the impulsive nature of the piling noise and the long duration
of operation which may be more than eight hours a day. This means that the noise dose to
people around a construction site may exceed the safety limit and hence may result in
temporary and permanent shifting of thresholds of hearing.
Hong Kong has a very high vehicle
density of about 200 vehicles per kilometers of road. Due to this high vehicle density,
many main r ads in Hong Kong have daytime traffic volume of more than 3,000 vehicles per
hour, and sometimes may reach 4,000 vehicles per hour in the rush hours. Figure B5 shows
the time variation of the indoor sound pressure level due to the traffic at an adjacent
road over a 24-hour period.
Figure B5 24-Hour Indoor Traffic Noise
In Hong Kong, the presence of the
airport imposes very severe noise pollution on the highly populated areas under the flight
path. Because of the large number of people severely affected by aircraft noise, and
because of the tremendous costs involved to reduce the impact of this kind of noise,
aircraft noise has received more attention than any other environmental noise.