Visitors’ response to extraneous noise in countryside recreation areas
Kwai-cheong Chaua), Kin-che Lamb) and Lawal M. Marafac)
(Received: 11 December 2009; Revised: 1 June 2010; Accepted: 1 June 2010)
A growing body of literature has shown that the experience of visitors to the
countryside for nature appreciation and other outdoor activities can be
enhanced on one hand by natural sounds and degraded on the other by
extraneous noises emanating from aircraft, road traffic and visitors themselves.
It has also been postulated that the positive and negative effects of these natural
and extraneous sounds are defined by the ambient acoustic setting and the
context defined by the landscape, human aspirations, and activities undertaken
by the visitors. A study was undertaken in the Country Parks of Hong Kong,
aimed at characterizing the extraneous noise intrusions and determining their
effects on the response of Country Park visitors. A questionnaire survey was
administered to over 700 visitors, and acoustic measurements were made, at
several locations representing different contexts. The study found that the
ambient acoustic setting did have an effect on human response to extraneous
noise. Similarly, the types of activities undertaken by the visitors mediated their
annoyance reactions toward extraneous aircraft noise. The results provide a
scientific basis to help formulate policies and plans for the protection and
management of countryside soundscapes. © 2010 Institute of Noise Control
Engineering.
Primary subject classification: 52.7; Secondary subject classification: 56.3
1
INTRODUCTION
As noise pollution becomes a more and more serious
problem in cities, the countryside is seen as a refuge
where urban dwellers can escape from the stresses of
urban living and rejuvenate themselves physically and
psychologically1,2. To properly manage and protect the
countryside acoustic environment, it is important to
understand how countryside visitors appraise the
soundscape and respond to noise intrusions. A growing
body of literature has emerged indicating that human
enjoyment of the countryside environment can be
enhanced on the one hand by natural sounds and
compromised on the other by noise emanating from
human and mechanical sources3–6. A recent study
a)
b)
c)
Department of Geography and Resource Management,
The Chinese University of Hong Kong, Shatin, New Territories,
HONG
KONG
SAR;
email:
[email protected].
Department of Geography and Resource Management,
The Chinese University of Hong Kong, Shatin, New Territories,
HONG
KONG
SAR;
email:
[email protected]. (Coressponding author)
Department of Geography and Resource Management,
The Chinese University of Hong Kong, Shatin, New Territories,
HONG
KONG
SAR;
email:
[email protected].
484
Noise Control Eng. J. 58 (5), Sept-Oct 2010
undertaken by the authors indicates that people generally prefer natural sounds and dislike non-natural ones,
and that their overall preference for a particular soundscape depends very much on the presence or absence of
these natural and non-natural sounds7. Due to increasing motorization and mobility as well as the booming
tourist industry, the countryside is not immune to sonic
intrusions. The literature is replete with examples of
how a tranquil environment can be impaired by extraneous noises from aircraft, road traffic and visitors7–11.
However, the annoyance reactions of countryside
visitors to extraneous noise are probably very
complex12. Staples13 observed that there are no simple
answers to the question of what determines which
people, doing what things, in what place, will be
annoyed by noise in the countryside. In addition to the
number of noise events and exposure levels6,10, it has
been reported that annoyance can be related to personal
attitudes12, noise exposure at home vis-a-vis in the
outdoor environment and recent changes in noise
exposure1,14,15. Also important is the context in which
the recreational activities and noise intrusions take
place and the outdoor experience is formed and
whether the extraneous sound is out of place or congruent with the expectations of the recreationists16,17.
Visitors’ expectations are shaped by the landscape and
Fig. 1—Conceptual framework of visitor response
to extraneous noise.
physical setting as well as by their own motivation and
activities (Fig. 1). The physical setting together with the
landscape features also shape the ambient sound level,
which in turn determines whether, and to what extent,
the extraneous noise is noticeable. Audibility is known
to be a key factor affecting annoyance reactions to
intrusive sound16,18,19.
The two forms of extraneous noise examined in this
study are aircraft noise and sound caused by the
visitors, including human conversation, screaming,
shouting, and sounds of play. Road traffic noise is both
an extraneous noise and a noise in the background
which can mask other intrusive noise. This study
focuses on road traffic noise as a masking agent.
The study reported here is part of a larger research
project7 aimed at characterizing the countryside soundscapes of Hong Kong and unravelling how visitors
appraise the soundscape and react to extraneous noise.
In this study, we specifically examine whether or not
human response to extraneous noise is (1) dependent
on ambient sound; and (2) conditioned by the types of
activities undertaken by the countryside visitors. The
results of this study should provide a scientific basis for
countryside planning and management.
2
STUDY AREA
The study was undertaken in two Hong Kong
Country Parks which are popular outlets for outdoor
recreational activities. In spite of the huge development
pressure in Hong Kong, about 40% of the land area of
Hong Kong has been designated as country parks
which are unspoiled, clean and green areas protected
from further urban development. Located in the
subtropics, Hong Kong’s countryside boasts a long
coastline, great altitudinal variation, rich biodiversity
and a diverse assemblage of landscape features. All
these have made the countryside a valuable natural
Noise Control Eng. J. 58 (5), Sept-Oct 2010
Fig. 2—Study sites and aircraft flight path.
asset for Hong Kong’s seven million people. Our recent
survey shows that among its various attributes, the
acoustic environment is the third most important factor
attracting people to the countryside, outranked only by
the beautiful scenery and clean air7. Similar to National
Parks and wilderness areas in other countries, the
country parks of Hong Kong are not free from noise
intrusions from airplanes, road transport, and visitors.
The present study took place in the Sai Kung and
Shing Mun Country Parks (Fig. 2), both within
half-hour’s drive from the city. Situated on Hong
Kong’s eastern extremity, the Sai Kung Country Park is
endowed with lofty peaks, green slopes, beautiful
beaches and tinkling brooks. It is a popular spot for
camping, hiking, picnicking, barbecuing and scenery
appreciation. The Shing Mun Country Park is built
around a reservoir with tranquil water bodies and quiet
hills. It is a popular spot for picnicking and nature
appreciation. Both country parks are under or close to
flight paths of airplanes landing at and taking off from
the Hong Kong International Airport (Fig. 2). Most of
the aircraft noise events are caused by passenger jets
flying at an altitude of more than 1 km above the study
sites. Scenic flights operated by small aircraft and helicopters are very rare in the study area. Visitors to both
Country Parks are mainly local residents of Hong Kong
who patronize the countryside for various reasons. Only
parts of the country park are served by public roads; other
parts are served by walking trails or secondary roads with
limited public access.
3
MATERIALS AND METHODS
To examine whether human response to extraneous
noise in the countryside is dependent on the ambient
acoustic setting and types of activities undertaken by
the respondents, face to face interviews with visitors
were undertaken at different sites (Fig. 2) situated in
485
Table 1—Characteristics of study sites.
A
Group
Quiet sites
Location
Chui Tung Au (Site 2)
Site Description
Saddle between 2 hills on a
nature trail in the Country
Park, no roads within 2 km
radius
Small hills and valleys
surrounding the reservoir
with picnic areas, served by
an access road
Picnic/barbecue area on
foot slope, shielded and
⬎150 m from nearest road
Beaches and sea cliffs
opening to the sea, no road
access
Picnic/BBQ areas adjacent
to a road and within 300 m
from coast
Shing Mun (Site 6)
Pak Tam Chung (Site 3)
B
Seashore Site
Sai Wan (Site 1)
C
Picnic areas abutting a road
in the Country Park
Tai Mong Tsai (Site 4)
Shui Long Wo (Site 5)
No. Visitors
Interviewed
94
Total
145
144
180
52
110
725
* Study site numbers are same as those in Fig. 2
different natural settings (Table 1 and characterized by
different acoustic environments.
3.1
Site Selection
A total of six study sites, located in two Country
Parks, were purposefully selected as interview
locations for countryside visitors. These sites can be
grouped into 3 categories: quiet sites (A), seashore
sites (B), and sites abutting roads (C) serving the
Country Park (Table 1). Because of the different natural
setting and facilities at these sites, the major activities
undertaken by the visitors at these sites are somewhat
different (Table 2).
These sites are scattered over a distance of some
10 km, with some closer to the flight path than others
(Fig. 2). Generally speaking, sites to the east are farther
away from the flight path and are hence less exposed to
aircraft noise. The three quiet sites are located at different
locations relative to the flight path as a result of which
differences due to location are probably obscured. Interpretation of the results should take into account differences in location and specificity of various sites.
3.2
Interview of Countryside Visitors
Interview with the countryside visitors was
conducted four times at each site, covering one
weekday (Friday) and one weekend (Saturday/Sunday)
both in the winter (December 2006) and spring season
(March 2007). The face to face interviews were undertaken between 1000 h and 1630 h during when sound
measurements were taken. Owing to the limitation in
trained personnel and sound monitoring equipment, the
Table 2—Main activity undertaken by visitors at different sites.
Main Activity
A
B
C
Group
Quiet sites
Seashore
Roadside picnic areas
All Sites
Sample Size
383
180
162
725
Hiking/
Scenery Appreciation
73.7%
95.0%
37.0%
69.7%
505
Hiking/scenery appreciation also includes relaxation, nature photography and cycling
Picnicking/barbecue includes social or family gathering
“Others” include camping and visits to old villages and cultural heritage sites
486
Noise Control Eng. J. 58 (5), Sept-Oct 2010
Picnicking/
Barbecue
22.8%
0.6%
54.3%
24.0%
174
Others
3.5%
4.4%
8.7%
6.3%
46
interview and simultaneous sound measurement could
only be undertaken at any 3 of the 6 study sites on any
particular sampling day. Interviews at the quiet sites were
undertaken at trail sides close to resting places or scenic
spots; interviews at the seashore site were undertaken on
the beach or at resting areas; and interviews at the
roadside sites were undertaken in parking lots, picnic or
barbecue grounds. The survey targeted visitors aged
18 years or above who have been at, or for walkers on
trails, in the close vicinity of, the interview site for at least
15 minutes. Most of the interviewees were Hong Kong
residents from the city. The overall response rate was 51%
which can be considered acceptable considering some
potential interviewees were on the move. The weather was
fine on all days of interview, without rain and strong
winds which might influence the visitors’ perception of
the sonic environment.
The purpose of the survey was initially masked,
being posed as a general survey of visitor perceptions
of the environmental quality of the countryside.
Respondents were asked, in either Cantonese or
English depending on the language used by the respondent, a number of questions about their perceptions and
experience in the immediate environs of the site with
reference to that particular 15-minute period prior to the
interview. The questions included: (a) what sound they
had heard in the vicinity of the site; (b) which was the
most liked and disliked sound; (c) whether they had heard
any aircraft sound or sound caused by other people in the
last 15 minutes; (d) how much they disliked the aircraft
and human-caused sound on a scale of 1 to 7 共1 = not at
all; 7 = very much); (e) how much they were annoyed by
the aircraft and human-caused sound on a scale of 1 to 7
共1 = not at all; 7 = very much); (f) why they had chosen to
visit the site; (g) what they had planned to do; and (h)
some personal data. We believe the answers to questions
(f) and (g) may indicate the visitor’s motivation and expectations. In order not to introduce any bias, the term
“sound,” rather than “noise,” was used in the interview to
refer to the sound from aircraft and human sources.
from any prominent sound source. The sound was
recorded in 24-bit wave format with a sampling
frequency of 48 kHz. On return to the laboratory, the
audio signals were transferred to a B&K model 2250
Investigator in conjunction with B&K Application
Software Evaluator Type 7820–7821 to determine
commonly used acoustic metrics such as LA10, LA50,
LA90, LAeq and 3rd octave frequency spectrum in
one-second intervals for the measurement period from
1000 h to 1630 h. These digital data were used to
prepare spectrograms portraying the variation of sound
intensity and spectral characteristics over time20.
In addition to the afore-mentioned automatic
continuous audio recordings, field workers were
deployed to each measurement site to make aircraft
noise measurements using portable B&K model 2250
sound level meters. To measure the noise from
over-flying aircrafts, trained field workers were
deployed to specially selected locations which are far
away, or acoustically shielded, from the sea, roads or
streams. These workers listened attentively to the
aircraft noise, noted down the start and end time of
each noise event, and stored the acoustic data of each
event in the sound meter. Back in the laboratory, the
acoustic characteristics of the noise events are retrieved
and expressed in terms of LAeq, event and LAmax.
3.4
The interview data obtained were analyzed using
Statistical Package for the Social Sciences (SPSS)
version 14.0 for Windows. The visitors’ reactions to
aircraft and human-caused noise among the three
groups of sites were contrasted using ANalysis Of
VAriance (ANOVA). Human response to different
sounds between those who visited the countryside for
hiking/scenic appreciation and those who visited for
barbecue/picnicking was compared by T-Test.
4
4.1
3.3
Sound Recording and Acoustic
Measurements
On the same day of interview, digital sound recordings were taken using a Marantz PMD671 Portable
Digital Audio Recorder with a Brüel & Kjær (B&K)
model 4188 microphone (Type 1) and model 2671
microphone preamplifier. Owing to the limitation in the
availability of equipment, only 3 sets of automatic
recording equipment could be deployed at any time. By
assigning the instruments to different sites, we believe
representative and comparable samples of the acoustic
conditions at these sites were obtained. The instrument
was set up at a place hidden from the visitors and away
Noise Control Eng. J. 58 (5), Sept-Oct 2010
Statistical Analysis
RESULTS
Acoustic and Visitor Profile
The acoustic characteristics of the study sites on one
of the sampling days in the spring season of 2007 are
shown in Table 3. It is evident that sites of the quiet
group (A) are notably lower in sound level than those of
the other two groups. Within the quiet group, Site 2 is
the quietest because it is located far away from the
roads, streams and sea. The ambient sound levels, as
represented by LA90, of Sites 3 and 6 are slightly higher
than that of Site 2 because they are constantly exposed to
distant, albeit weak, road traffic and human sound, respectively. Among the 3 groups, Group B, as represented by
Site 1, exhibits the highest overall sound level because of
the sea waves. Sites 4 and 5 are picnic/barbecue sites
487
Table 3—Acoustic characteristics and aircraft noise at different sites.
Acoustic Characteristics of the Sites
1000 h – 1600 h (dB)
Group
A
B
C
Location
Chui Tung Au
Pak Tam Chung
Shing Mun
Sai Wan beach
Tai Mong Tsai
Shui Long Wo
Site
2
3
6
1
4
5
LAeq
34
40
41
63
49
50
LA10
35
44
43
64
52
48
LA50
31
34
41
63
47
40
Aircraft Noise Events
(Mean, dB)
LA90
29
32
34
61
43
36
LAeq,event
44
46
50
46
48
48
LAmax
53
54
56
53
54
55
Sound measurements on a Friday in the spring of 2007.
LAeq refers to noise from all sources.
LAeq,event refers to noise measured during aircraft overflight at locations shielded from the sound from sea waves, road traffic
and running water.
adjacent to an access road serving the country park and
nearby villages. In addition to traffic noise, the sounds
from birds, insects and trees form the background at Sites
4 and 5.
The activities undertaken by visitors could be
grouped into 3 major categories (Table 2). Nature
appreciation (hiking, scenery appreciation and meditation) was the main activity undertaken by 69.7% of the
visitors. Another 24% of visitors went to the countryside primarily for picnic, barbecue or family/group
activities. The remaining 6.3% were engaged in a great
variety of other activities including camping and visiting historical settlements and heritage sites. Generally
speaking, a relatively large proportion of people visiting the quiet and seashore sites also took part in hiking
and nature appreciation activities, whereas more people
at the roadside sites were engaged in picnic and barbecue activities.
4.2
Human Preference for Different Sounds
at the Study Sites
As mentioned above, respondents were asked to
name the sounds they had heard using different
questions during the interview. Initially, they were
asked to name spontaneously all the sounds heard in
the vicinity of the site. Later in the interview, they were
asked again whether they had heard any aircraft or
human sound in the past 15 minutes. Human sound is
generally taken to mean human voice, conversation, chit
chat, screaming and shooting. It does not include radio,
music and any sound from machines. As can be seen in
Table 4, bird song was the most frequently named sound,
mentioned by 67.7% of the respondents. It was followed
by sounds of the wind, waves and insects. Among the
non-natural sounds, the most frequently mentioned ones,
in order of frequency of occurrence, were human, road
traffic and aircraft. It is noteworthy that, upon prompting,
a higher proportion of the visitors reported human and
aircraft sounds. For example, almost 86% of visitors were
aware of the existence of human sound when prompted, as
compared to 53% when they were not. In contrast to
human sound, the percentage of visitors reporting aircraft
sound increased only by 8% when prompted. These
findings indicate that human sound is ubiquitous, and
many countryside visitors are not conscious of its
Table 4—Sounds heard and reported by visitors expressed as percent of respondents in different groups.
Prompted
Responsea
Impromptu Response
Group
A Quiet sites
B Seashore
site
C Roadside
sites
All Sites
a
Wind
48.6%
62.2%
Running
Water &
waterfall
15.9%
17.2%
Waves
10.7%
100%
Road
Traffic
49.6%
0.0%
Aircraft
38.1%
27.8%
Human
59.3%
41.6%
Aircraft
49.8%
35.5%
Human
90.6%
88.3%
38.3%
45.7%
6.2%
11.7%
98.1%
29.6%
52.5%
33.3%
80.6%
214
29.5%
372
51.3%
102
14.1%
239
33.0%
349
48.1%
244
33.7%
387
53.3%
305
42.1%
622
85.8%
Sample
Size
383
180
Birds
78.1%
37.2%
Insects
33.7%
12.8%
162
77.2%
725
491
67.7%
Respondents were asked to name as many sounds as they had heard.
488
Noise Control Eng. J. 58 (5), Sept-Oct 2010
Table 5—The sound most liked and disliked by countryside visitors.
Most Liked Sound
Group
Quiet sites
Seashore site
Roadside picnic
sites
All
Count
Groups % within row
Most Disliked Sound
Group
A
B
C
A
B
C
All
Groups
Quiet sites
Seashore site
Roadside picnic
sites
Count
% within row
Valid
Sample
Size
382
180
162
Birds
61.0%
5.6%
56.8%
Waves
6.8%
84.4%
8.0%
Wind
18.3%
5.6%
11.7%
Running
water &
waterfall
5.8%
1.1%
3.1%
724
335
46.3%
191
26.4%
99
13.7%
29
4.0%
27
3.7%
24
3.3%
6
0.8%
13
1.8%
Valid
Sample
Size
354
171
153
Road
traffic
Aircraft
Human
Radio/
Music
Insects
Others
None
38.1%
0.0%
81.7%
13.6%
15.2%
3.9%
11.3%
17.0%
2.0%
Dogs &
other
animals
5.1%
5.3%
2.6%
2.3%
3.5%
2.6%
2.0%
2.9%
2.0%
1.1%
1.8%
1.3%
26.6%
54.4%
3.9%
260
38.3%
80
11.8%
72
10.6%
31
4.6%
18
2.7%
15
2.2%
9
1.3%
193
28.5%
678
presence unless prompted. On the other hand, aircraft
noise is probably regarded as extraneous, and most people
could name it without prompting.
The study findings also shed some light on which
sounds countryside visitors liked and disliked most
(Table 5). Consonant with the findings of an ancillary
study undertaken by the study team7, natural sounds are
favored over non-natural ones, while human and
mechanical sounds are disliked most. The two most
favored natural sounds are bird songs and waves, and
the non-natural ones disliked most are road traffic and
aircraft noise. The results in Table 5 should however not
be taken as evidence of differential preference for
different sounds in the Hong Kong countryside,
because not all sites are exposed equally to all sounds.
The results reflect both the prevalence of different
sounds at different sites as well as countryside visitors’
liking of these sounds.
4.3
Human Response to Aircraft and HumanCaused Noise
To elucidate how countryside visitors respond to
extraneous noise from aircraft and from other visitors,
two questions were posed with respect to each sound
source (Table 6). Those questions focused on “dislike”
and “annoyance” which are two different dimensions of
the human feeling. For instance, one may dislike a
particular sound but may not be annoyed by it to the
same extent as one dislikes it. The subtle difference
Noise Control Eng. J. 58 (5), Sept-Oct 2010
Insects
3.9%
0.0%
7.4%
Human
3.1%
1.1%
6.2%
Dogs &
other
animals
0.5%
0.6%
1.9%
Others
0.5%
1.7%
4.9%
between the two can be seen in the interview results
(Table 6). The results show that visitors showed their
dislike and annoyance for both aircraft and humancaused noise, although their dislike was more strongly
identified than their annoyance.
Reading the data in Table 6 in conjunction with
those in Table 4 shows that while significantly more
countryside visitors are aware of human sound, their
feelings of dislike and annoyance toward human sound
are not as strong as those towards over-flying aircraft.
This is probably because aircraft noise is deemed
“extraneous” whereas human sound is self-generated.
4.4
Effects of Masking and Activity on
Human Response
It is commonly believed that human response to
extraneous noise can be moderated by the ambient
sound level and the activities undertaken by the
countryside visitors. Ambient sound level matters
because of its masking effect16,18. A high background
sound level can render the extraneous sound less
audible and hence less annoying. The type of activities
undertaken by the visitor is also a determinant of
human response, probably because extraneous noise
may disturb or detract from the activity being undertaken. Conversely, the type of activity may also capture
the attention of the visitors to such an extent that their
sensitivity to extraneous noise is subdued.
489
Table 6—Visitors’ dislike and annoyance rating of aircraft and human-caused sound on 7 point scale at
different sites (1 = not at all; 7 = very much).
A
Group
Quiet sites
Sample
Size
383
B
Seashore site
180
C
Roadside picnic
areas
All Sites
162
725
How much do
you dislike
aircraft sound?
Mean Score
(Std Deviation)
5.83
(1.18)
5.73
(1.14)
4.77
(1.26)
5.61
(1.26)
The results in Table 6 show that there are differences
in the degree of dislike and annoyance among the 3
groups of sites. Levels of dislike and annoyance are
higher at the quiet and wave masked sites (Groups A
and B) than at the roadside traffic noise masked site
(Group C), despite the fact that levels of aircraft noise
at the seashore site (Group B) are slightly lower (Table
3). It is interesting to note that even though the ambient
sound level of waves (Group B) is higher than that of
traffic noise (Group C), the effect of masking, as shown
in the data of Table 6, is less prominent.
The effect of masking can be confounded by the
types of activities undertaken by the respondents. The
survey data (Table 7) show that the level of dislike and
annoyance is generally higher among those engaged in
hiking and scenery appreciation activities than those
visiting the site for picnic, barbecue and meeting with
family members and friends.
How much are
you annoyed
by aircraft
sound?
Mean Score
(Std Deviation)
3.81
(1.75)
3.68
(1.44)
2.12
(1.45)
3.46
(1.76)
How much do
you dislike
human sound?
Mean Score
(Std Deviation)
4.33
(1.51)
4.46
(1.36)
3.75
(1.09)
4.26
(1.42)
How much are
you annoyed
by human
sound?
Mean Score
(Std Deviation)
3.03
(1.50)
2.30
(1.23)
2.41
(1.31)
2.72
(1.43)
To ascertain whether the observed differences in
visitor response among different sites and activities are
statistically significant, the data were subjected to
further statistical analysis. The ANOVA test was used
to determine if the degree, separately, of dislike and
annoyance towards aircraft noise is significantly different among the three groups (quiet, seaside and
roadside) of sites. The results show that the differences
are indeed statistically significant 共p ⬍ 0.001兲. The
same test was similarly applied to the visitors’ degree of
dislike and annoyance towards human-caused noise and
the differences were found to be statistically significant
共p ⬍ 0.05兲. These differences can possibly be attributed to
the masking effect of the ambient sound. To contrast the
degree of dislike and annoyance towards extraneous noise
between those who go the countryside for hiking/nature
appreciation and those who go for picnic/BBQ, the T-Test
was used. The results confirm that observed differences in
Table 7—Visitors’mean dislike and annoyance rating of aircraft and human sound on 7 point scale grouped
by activities undertaken by visitors (1 = not at all; 7 = very much).
How much dislike?
Aircraft sound
Activity
Hiking/
Scenery
appreciation
Picnic/
Barbecue
Overall
490
N
193
50
243
Mean Score
(Std Dev)
5.74
(1.16)
5.10
(1.51)
5.59
(1.27)
Noise Control Eng. J. 58 (5), Sept-Oct 2010
How much annoyed?
Aircraft sound
N
235
53
288
Mean Score
(Std Dev)
3.69
(1.71)
2.77
(1.76)
3.42
(1.75)
How much dislike?
Human sound
N
321
99
420
Mean Score
(Std Dev)
4.40
(1.42)
3.85
(1.21)
4.27
(1.40)
How much annoyed?
Human sound
N
503
141
644
Mean Score
(Std Dev)
2.77
(1.43)
2.68
(1.38)
2.73
(1.43)
the degree of dislike as well as annoyance with respect to
aircraft noise are statistically significant between the two
groups of people engaged in different activities 共p
⬍ 0.01兲. As far as human-caused noise is concerned, the
between-group differences are only significant in terms of
the degree of dislike 共p ⬍ 0.05兲 but not in terms of annoyance 共p ⬎ 0.05兲.
5
DISCUSSION
As more and more people move to and live in cities,
the countryside provides an important respite, both as
an outlet for recreation and a place for self-restoration.
People enjoy the countryside not only because of its
scenery, greenery and air quality, but also because of its
sonic environment. A tranquil and peaceful countryside
can provide the urban dwellers with a sonic refuge and
restorative environment. There is, however, an increasing concern that the sonic environment is being
degraded by extraneous mechanical and human
noises4,8. The Hong Kong countryside provides an
experimental base to test how visitors appraise the
soundscape and respond to extraneous sounds emanating from aircraft and other visitors. The results
described in the preceding sections show that visitors’
responses were different with respect to the two extraneous sound sources and at different study sites. Different responses were also observed among visitors going
to the countryside for different activities. All these
differences merit further discussion.
Of the extraneous noises investigated in this study, it
would be interesting to contrast visitors’ response to
these two sources (aircraft and human-caused sound).
The results presented in the preceding sections indicate
that visitors are generally less conscious of human
sound than aircraft noise. Furthermore, despite the
ubiquitous occurrence of human sound in outdoor
recreation areas, feelings of dislike and annoyance are
both lower for human sound than for aircraft noise. We
believe when a sound is heard in the countryside, the
visitor interprets its meaning and evaluates its congruence with the setting and potential interference with the
activities being undertaken. Hence, the observed differential response can be understood from two perspectives, namely congruence and interference. From the
perspective of congruence, the observed differences in
human response could probably be ascribed to the fact
that aircraft noise is extraneous, emanating from activities that are not related to outdoor recreation; whereas
human sound is not entirely “out of place” as it is the
outcome of recreational and social activities undertaken by the visitors themselves. From the perspective
of interference, aircraft noise can distract the visitor’s
attention, particularly if the main goal of countryside
visitation is scenic appreciation and hiking; whereas
Noise Control Eng. J. 58 (5), Sept-Oct 2010
the human-caused noise is not so much a problem
particularly if visitors come as a group for barbecue
and picnic. The above is of course a plausible explanation which has to be further validated with a special
experimental design and questionnaire.
Another finding of the study that warrants further
investigation is that, in comparison with the quiet sites,
people at the roadside picnic areas were generally less
sensitive to, and annoyed by, aircraft noise (Table 6).
Conversely, visitors at the seashore site were more
conscious of, and annoyed by, aircraft noise despite the
background noise level is much higher at the seashore
site. Whether this differential response was due to the
masking effect of the rumbling traffic noise at the
roadside site or due to other factors is an issue yet to be
resolved. We noted, and so did the visitors at the
seashore site, that relative to the natural wave sound,
the noise from over-flying aircrafts is still noticeable.
We are not sure if the differential response could be
attributed to openness of the seashore site where
passing aircrafts can be seen as well as being heard.
This is an intriguing question that general explanations
are not sufficient and further research is warranted.
The study also investigated whether or not the types
of activities undertaken by countryside visitors can
mediate human negative response to extraneous noises.
As postulated, those who go to the countryside for
picnic/barbecue or for family/group activities are
generally less annoyed by aircraft noise than those who
go for hiking or scenery appreciation. This mediating
effect is, however, less prominent with respect to
human-caused noise. Our findings are consonant with
those reported by Kariel17, who showed that visitors’
annoyance levels to the same noise can vary with the
purpose of the trip and activities undertaken. However,
why there is such a difference between these two extraneous noises has yet to be elucidated and is a topic that
merits further investigation.
While the above research findings indicate that
human response to extraneous noise in the countryside
can be moderated by the ambient sound and the type of
activities being undertaken, it is worthy to note that the
effects of these influencing factors are confounded. For
example, the visitors at different sites may have gone
there with different motivation and aspirations. Further
study is needed to isolate these influencing factors and
to probe specifically why visitors respond differently at
different sites.
Discussion of the study findings will not be
complete without noting on the role of road traffic
noise in the countryside setting of Hong Kong. While
the current study focused only on aircraft and human
sound as extraneous noise sources, the potential role of
road traffic as an extraneous noise source should not be
491
ruled out. The data obtained do point to some intriguing phenomenon which merit further investigation. For
example, at the roadside sites, nearly everyone heard
road traffic, of whom 82% disliked it (Table 5);
whereas at the quiet sites, only 50% heard traffic noise
and 38% disliked it. The latter gives a percentage of
nearly 80% which is similar to that at the roadside sites.
The data suggest that people in quiet areas may still be
sensitive as traffic noise even though the levels are
probably lower then they are at roadside sites.
The above discussions suggest that human response
to extraneous noise in the countryside is a highly
complex matter. The study has answered some
questions and raised a few others which can probably
be answered with a sharpened focus and research
design. The findings of the current study, in spite of the
limitations, do provide some pertinent information
contribute to the understanding of human response to
different sounds in an outdoor countryside setting.
6
CONCLUSIONS
An interview with over 700 visitors was undertaken
in the Country Parks of Hong Kong which provide an
important restorative environment for the urban
population. A visitor survey undertaken at six sites
representing different ambient sound settings indicated
that the visitors’ response to aircraft and human-caused
noises can be different because of different masking
effects of the sounds of waves and road traffic. The
visitors’ negative responses are the strongest at the
quiet sites. Of the two masking sounds, the moderating
effects of road traffic, probably because of its continuous rumbling character, is greater than that of waves.
The study also shows that the visitors’ feelings of
dislike and annoyance towards intrusive noise are
mediated by the type of activities they undertake in the
countryside. People going to the countryside to hike
and appreciate scenery have generally stronger
negative feelings towards noise intrusions. These
findings highlight the complexity of human response to
extraneous noises in the countryside, and the effects of
ambient sound and the natural setting on human
reactions.
7
ACKNOWLEDGMENTS
The work described in this paper was substantially
supported by a grant from the Research Grants Council
of the Hong Kong Special Administrative Region,
China (Project No. CUHK 4629/05H). The assistance
of Kin-Pui Lui, Pak-kin Chan and Fung-wai Lui in field
work and that of Teresa Chung and Vivian Tse is grate-
492
Noise Control Eng. J. 58 (5), Sept-Oct 2010
fully acknowledged. We thank the anonymous reviewers for their constructive comments on an earlier draft
and Mary Felley for proof reading the manuscript.
8
REFERENCES
1. B. de Coensel and D. Botteldooren, “The quiet rural soundscape
and how to characterize it”, Acta. Acust. Acust., 92, 887–897,
(2006).
2. S. Kaplan, “The restorative benefits of nature: Toward an integrative framework”, Journal of Environmental Psychology, 15,
169–182, (1995).
3. L. Brown, “Rethinking ‘quiet areas’ as areas of high acoustic
quality”, InterNoise06, (2006).
4. B. Rossman, “Impairment of park soundscapes”, The George
Wright Forum, 21, 18–21, (2004).
5. M. Downing, “Characterising ambient soundscapes and noise
intrusions”, InterNoise06, (2006).
6. E. J. Pilcher, P. Newman and R. E. Manning, “Understanding
and managing experiential aspects of soundscapes at Muir
Woods National Monuments”, Environ. Manage. (N.Y.), 43,
425–435, (2009).
7. K. C. Lam, A. L. Brown, L. Marafa and K. C. Chau, “Human
preference for countryside soundscapes”, Acta. Acust. Acust.,
96, 463–471 (2010).
8. B. Krause, “Loss of natural soundscape: Global implications of
its effects on humans and other creatures”, San Francisco World
Affairs Council, (2001).
9. G. M. Aasvang and B. Engdahl, “Subjective responses to aircraft noise in an outdoor recreation setting: a combined field and
laboratory study”, J. Sound Vibr., 276, 981–996, (2004).
10. G. P. van den Berg, “Observed prevalence of transport sounds in
quiet areas”, InterNoise04, (2004).
11. D. Beal, “Campers’ attitudes to noise and regulation in Queensland National Parks”, Australian Parks & Recreation, 30, 38–
40, (1994).
12. B. L. Mace, P. A. Bell and R. J. Loomis, “Visibility and Natural
Quiet in National Parks and Wilderness Areas: Psychological
Considerations”, Environ. Behav., 36, 5–31, (2004).
13. S. L. Staples, “Comment on ‘Effects of aircraft overflights on
wilderness recreationists’ [J. Acoust. Soc. Am. 100, 2909–2918
(1996)]”, J. Acoust. Soc. Am., 104(3), 1726–1728, (1998).
14. N. H. Krog and B. Engdahl, “Annoyance with aircraft noise in
local recreational areas, contingent on changes in exposure and
other context variable”, J. Acoust. Soc. Am., 116, 323–333,
(2004).
15. N. H. Krog and B. Engdahl, “Annoyance with aircraft noise in
local recreational areas and the recreationists’ noise situation at
home”, J. Acoust. Soc. Am., 117(1), 221–231, (2005).
16. G. Brambilla, “Responses to noise in urban parks and in rural
quiet areas”, Acta. Acust. Acust., 92, 881–886, (2006).
17. H. G. Kariel, “Factors affecting response to noise in outdoor
recreational environments”, Can. Geographer, 34(2), 142–149,
(1990).
18. P. D. Schomer and L. R. Wagner, “On the contribution of noticeability of environmental sounds to noise annoyance”, Noise
Control Eng. J., 44(6), 294–305, (1996).
19. L. M. Anderson, B. E. Mulligan, L. S. Goodman and H. Z. Regen, “Effects of sounds on preferences for outdoor settings”,
Environ. Behav., 15, 539–566, (1983).
20. P. L. Li, K. C. Lam, L. M. Marafa, W. W. So and K. C. Lee,
“Understanding the temporal variation of countryside soundscape of Hong Kong”, InterNoise07, (2007).