CONFIDENTIAL
To ascertain the effect of this level of exposure on indoor activities, the noise reduction properties of building walls and windows must be considered. Air conditioned and heated environments may attenuate outdoor levels by 20 dB (Reference
4).
Open window dwellings typical in Hong Kong may only provide 4 dB of attenuation (Reference 5). In the former case, indoor maximum levels would reach only 55 dB in the worst case, which would have negligible effects on activities such as conversation and sleep.
In the latter case, with windows open, the 70 dB maximum level would be more noticeable and under some circumstances can interfere with conversation and disrupt sleep. The degree to which this would be annoying is a matter deserving further study. Including flights by other aircraft, average maximum levels are likely to be below 65 dB(A) under this condition. These events would occur on 70 percent of the days of the year, from about once every three minutes during the peak afternoon hour to about once every 25 minutes at night, if there were no early turn restrictions. Levels in the San Tin area estimated to be about 3 dB below these values, and overflights would occur at slightly greater frequencies.
In summary,
are
while single aircraft over flights will often be noticed in these areas their adverse effects cannot be characterized as widespread and severe. Consultants believe that only with further study of the issue could predicted problems be pinpointed more exactly and could the most acceptable solutions
be identified.
3.2
OTHER NOISE SOURCES
Other airport related noise sources contribute a small degree noise exposure around an airport. These were not examined in detail, but the following remarks can be made:
3.3
1
2.
3.
Aircraft maintenance and engine test activities are expected to contribute only slightly to noise levels in the vicinity of the airport proper. Such activities should only add a slight bulge to noise contours in the Tsim Bei Tsui penninsula area, if at all.
to
Helicopter service to and from Kowloon, Hong Kong and Macau could add to noise exposure in some areas, but details of routes and frequency must await further study.
Increased road traffic, rail movements, and construction are all concommittant with development of a new airport, however their effects on the area are not investigated in this study.
FUTURE NOISE LEVELS
If operations increase beyond the number assumed to apply in 1995 noise exposures would increase. The extent to which the introduction of quieter aircraft in the future would
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this increase is a matter for further study.
counteract
9-8
CONFIDENTIAL