Noise is unwanted
sound, but determining what is "unwanted" can be highly
subjective. What is music to one person may be a cacophony to another.
The roar of nearby traffic may disturb and distract one individual,
but barely be noticed by their neighbour. Tools have been developed
over the years to measure noise levels and determine which levels
are generally acceptable, but the results are often poorly understood
In Hong Kong,
noise problems are exacerbated by crowded living conditions. Most
people live in high-rise buildings, many of which are located next
to busy roads and commercial and industrial areas. More than 10
000 complaints are made about excessive noise each year. The Environmental
Protection Department (EPD) has introduced a number of measures
to control noise, yet misunderstandings persist. One key point is
that noise cannot be eliminated, only controlled. The department
is therefore endeavouring to improve the public's understanding
of noise and the many issues involved in reducing it to acceptable
Noise can be
measured in many different ways. The loudness, type of sound, duration,
time of day it occurs, and distance from the noise receiver can
all determine whether it is regarded as an unwanted intrusion. These
factors also complicate how noise can be measured and mitigated
against. The EPD has developed a tool that will help people understand
noise in all its complexities and learn how to prevent noise.
A noise education
website was launched in 2003, after being refined to make it more
user-friendly. Visitors can listen to different noise types, learn
how noise levels are calculated and understand different control
and mitigation measures, through interactive panels, text and illustrations
The general public can use the website to find out about common
noise sources and what can be done about unwanted noise. A version
for young people is also featured, which explains noise in simpler
One area that
is often controversial is the definition of "acceptable"
noise. The EPD uses the noise standard 70 decibel L10
(1 hour) to measure traffic noise, which indicates that noise has
exceeded 70 decibel one-tenth of the time (six minutes per hour)
during which the measurement was taken. This is regarded as a fair
measure of traffic noise nuisance. But how did that measurement
become the standard? The website explains that extensive research
in England in the 1960s found the L10
measurment correlated well with the community's tolerance and complaints
about traffic noise. The standard was formulated in the late 80s
after extensive field measurements in Hong Kong and a review of
similar standards in other developed countries. The website provides
many insights like these in order to illustrate that the noise standards
in Hong Kong have been well-researched and are not randomly determined.
Much of the
information on the website also has uses for professionals, such
as engineers, for whom noise may be a by-product of their work.
They can refresh their knowledge on the basic scientific principles
for analysing noise and look up real examples of mitigation and
control measures that have been used in Hong Kong. The website also
provides links to other sources of technical information.
to educate people about noise - and doing it in laymen's language,
rather than the technical jargon used by practitioners - is part
of the EPD's efforts to promote community understanding about environmental
noise. This was an objective in the Chief Executive's 2001 policy
address and the department is using other tools, in addition to
the website, to meet this goal. A CD-ROM on environmental noise
has been produced with input from more than 100 teachers, and includes
interactive features and information about various noise sources.
It will be distributed to schools, public libraries, district offices
and professional institutes in 2004. Education initiatives are also
being introduced for noise producers, such as the construction industry,
to help them address the problem.
noise has been a persistent source of complaint. In order to build
new buildings, tear down old ones or renovate existing premises,
it is inevitable that some noise is produced. The EPD has introduced
a number of measures over the years to restrict the times when noisy
work is allowed and to require that quieter equipment be used where
possible. Nonetheless, construction work is still a source of unwelcome
sound intrusion. The EPD must try to strike a balance between meeting
demand for a quieter environment, and not unduly interfering with
In order to
encourage operators to reduce their noise and obey the law, the
EPD has formed partnerships with the construction industry, vehicle
repair workshops, restaurants and property managers in recent years.
The four industries receive advice and support in controlling noise,
while the EPD gains a better understanding of the constraints and
opportunities they face. The partnership programme is helping to
reduce complaints and violations as these industries learn more
about how to control their noise (see Customer Service and Partnership
chapter for more details). In addition, education efforts are being
targeted at specific operators. The EPD and Highways Department
began staff exchanges in October 2003 to better understand each
other's work and it is hoped this will lead to a better appreciation
of road-related noise problems.
is also being used to smooth the way for operators to deal with
noise on a day-to-day basis. Operators can check instantly whether
their work will be carried out in an area designated for noise control,
through the EPD website (http://www.epd.gov.hk/epd/english/environmentinhk/noise/noise_maincontent.html).
They can also check to see if other noise permits have been issued
in the area, as all noise permits are now being published on the
website. Operators can use information about noise permits issued
for nearby construction sites when planning permit applications,
and adjust their work schedules to minimise disruptions. Self-assessment
tools are available on-line so builders can evaluate the likely
noise impact from their construction sites. Builders can also submit
their noise permit applications electronically.
of noise permits also helps the public to develop a better understanding
of noise control. People can visit the website to determine if a
site has a permit, how long the work will last and what conditions
have been attached to it, such as the times of day that noisy work
is allowed. One of the most annoying factors with noise is not knowing
when it will end. The noise permit information plugs that gap and
also indicates whether an operator is working outside their permitted
education is a two-way process. While the EPD can inform people
about noise standards and prevention, it is also working on
gaining a better understanding of the issue. Given the high-density
living of Hong Kong and the wide variety of noise sources,
there is much to learn about noise pollution here.
noise at home.
a crowded place.
a study was commissioned to obtain typical noise levels in
different parts of Hong Kong. The focus is on noise experienced
by people in daily life, in such places as the home, restaurants,
karaoke bars, game centres, concert halls, beaches, barbecue
sites, urban parks and country parks. Noise levels in the
home will be measured
different times of the day, while at other sites they will be
measured during the likely peak noise hours. The study will
also appraise the effectiveness of measures that have been introduced
to reduce traffic noise, such as podiums, purpose-built balconies,
architectural fins, barriers and low-noise road surfaces (see
box for details). The study will take about two years to complete
and it is hoped that it will provide information for formulating
new policies and measures to control noise.
Noise is annoying
but it is something that everyone in an urban environment must learn
to live with. The goal is to make it as acceptable as possible to
the majority of residents. This can be a difficult balance to achieve,
but the EPD hopes that by educating people and undertaking programmes
to reduce noise, it is moving towards making Hong Kong a quieter
barriers are a fact of life in most cities around the world,
where road, rail and air transport all increase noise levels.
Blocking out noise by barriers and enclosures is effective
in reducing the noise nuisance, and Hong Kong has built 38
kilometres of noise barriers and enclosures. But these have
come under criticism in recent years for their visual impact.
The EPD jointly organised an international seminar in December
2003 to look at the effectiveness and aesthetics of noise
160 professionals attended the event, which was jointly sponsored
by the EPD, Highways Department, Hong Kong Polytechnic University
and Hong Kong Institute of Acoustics. Speakers came from Australia,
Belgium, Britain and Japan, as well as Hong Kong. They discussed
such issues as theories of barrier design, methods for assessing
their performance, and new technologies. One subject that
sparked great interest was the visual impact of barrier design.
It was pointed out that many issues need to be resolved, such
as whether a barrier should stand out or blend into the background,
what attention should be paid to residents' view of the barrier,
and how to reconcile cost with demands for more attractive
barriers. The keynote speakers also noted that avoiding noise
problems through planning was the best solution.