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Proceedings of 20th International Congress on Acoustics, ICA 2010
23-27 August 2010, Sydney, Australia
ICA 2010 1
Assessment of railway soundscape in rural areas
Hyo Joo Yoo (1), Pyoung Jik Lee (1) and Jin Yong Jeon (1)
(1) Department of Architectural Engineering, Hanyang University, Seoul, Korea
PACS: 43.50.-X, 43.50.LJ,
ABSTRACT
In the present study, railway soundscape in rural areas was assessed by field measurements. Landscape merics of ru-ral areas were analysed, then a total of 10 sites were chosen covering different composition of landscape metrics. Au-dio-visual recordings were carried out at selected sites; acoustical characteristics of train noises were analyzed in terms of sound quality metrics, ACF (auto correlation function) and IACF (interaural cross correlation function) pa-rameters. It was found that noise levels of high speed trains ranged from around 70 and 90 dBA in terms of A-weighed equivalent noise levels. And it can be seen that IACC values of train noises were dependent on the layout of recorded sites, and perception of train noises were affected by background noise levels.
INTRODUCTION
The high speed train has been developed since the 1960s, particularly in Japan and Europe, and currently the high speed train has been adopted as a new transportation system in various countries. South Korea is the seventh country to develop a high speed train technology called the Korea Train eXpress (KTX). KTX was opened in 2004 and its maximum speed is around 300km/h. As the KTX has been used pro-gressively as a major transportation system, noise problem caused by the high speed train has grown from a local to a national issue. Many complaints from the residents and visi-tors in rural areas have been directed upon the maximation of the speed of the high speed train.Previously many studies have been focused on community response to high speed trains, which have are based on the social survey and mea-surement of sound pressure level [1,2]. However, the percep-tions of rural areas with high speed trains cannot be explained by only sound pressure levels since high speed trains are just one of the components of rural area consists of other va-riables. Therefore, perceptions of rural areas with high speed trains should be investigated as a concept of soundscape. In this study, audio-visual recordings were carried out in rural areas with high speed trains; acoustical characteristics of train noises were analyzed in terms of sound quality metrics, ACF (auto correlation function) and IACF (interaural cross corre-lation function) parameters.
RURAL SOUNDSCAPE
A rural area is an area outside of cities and towns which have a low population density, where noise levels are dependent on landscape metrics. The variation of noise levels in rural areas is larger, from quiet to noisy. However, in this study, only noisy rural areas have been investigated.
Table 1 shows nine landscape metrics which were chosen based on the research output of the landscape study [3,4]. Landscape metrics consists of two parts; natural and artificial features. Natural features contain agricultural crops, moun-tains, woods, and water features such as lakes and rivers. Artificial features include buildings, man-made constructions, traffic roads, elevated railways, tunnels, and noise barriers.
Sites for audio-visual recordings were selected on the basis of analysis of landscape metrics.
FIELD MEASUREMENT
Site Selection
There are two KTX lines in Korea; the Gyunbu and Honam line. In this study a total of 10 sites, along with these two lines, were selected for field measurement. They are located in the Gyungi province near Seoul, where both KTX lines pass through. Table 2 shows the charactersistics of 10 sites chosen in different landscape metrics, covering 9 codes, to obtain data from a wide range of rural soundscapes.
Table 1. Landscape metrics of rural area Code Description
Natural features
1 Agricultural crops (patch or rice field) 2 Undisturbed valley (mountain) 3 Woods 4 Water features (lake, reservoir, river)
Artificial features
5 Buildings and manmade constructions 6 Traffic road (highway / state road) 7 Elevated railway and bridge 8 Tunnel 9 Noise barrier
Table 2. Characteristics of sites
CodeSites
1 2 3 4 5 6 7 8 9 101 ○ ○ ○ ○ ○ ○ ○ ○ ○2 ○ ○ ○ ○3 ○ ○ ○ 4 ○ ○ ○5 ○ ○ ○ ○6 ○ ○ ○ ○ ○ ○ ○ ○7 ○ ○ ○ ○ ○ ○8 9 ○ ○ ○ ○
2
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3-27 August 201
Audio-visual r
From the field onducted at eacnd the binauraor the audio rec
menter and dumDuring the meaecorder (Fostex
n order to inveeption of sound
camcorder (Swere carried oudicularly away onducted at dahe assumption ng this period.
ANALYSIS O
Sound quality morrelation funcs well as sounderistics were acoustical chara
quality metrics:nd sharpness w
Pulse Software o
To observe the nd ACF were cn all calculationunning step watudy [5]. The he first maximuhe 1 and large
The IACC is the
When IACC is ion of the inco
hear the train no0.
Sound pressu
Table 3 shows tmbient noise w
dies indicated thLA90 as well aso explain the b
Coensel also poundscape as 4
Type
Train Noise
Ambient Noise
0, Sydney, Austr
recording
measurements,ch site. The du
al microphone (cording. The he
mmy head was aasurements, noix, FX2) and DA
estigate the effedscape, visual iSamsung, HMt at two positiofrom the railw
aytime from 11that outdoor ac
OF HIGH-SP
metrics and parction and interad pressure leveanalysed in ordacteristics of h: loudness, rouwere introducedof B&K.
ACF/IACF pacalculated for tns, the integratas 0.1 s, as a 1 and 1 are thum peak of the
er the 1, indicae maximum pea
1, the subjects oming train nooise but it is dif
ure level
the noise levelswithout high sphat percentile ns A-weighted eqbackground noiproposed the l1dBA in terms
Metrics
LAeq
LA10
LA50
LA90
LAmax
LAeq
LA10
LA50
LA90
LAmax
alia
audio-visual rummy head (Ty(Type 4101; Beight of the eararound 1.6 m frises were reco
AT (Sony, PC20
ect of visual imimages were caX-H106). Theons: 50 m and
way road. The r1:00 am to 3:00ctivities are mo
EED TRAIN
rameters extracaural cross corrl (LAeq) and fre
der to investigahigh speed traiughness, fluctud; these were c
arameters, the sthe duration of tion interval wasame manner
he delay time ane normalized Aate a lower andak of the norma
can clearly peroise, whereas thffused when IA
s of high speedpeed train noisenoise levels sucquivalent noise se level of ruralimit of quiet of LA50. LA50
1
80.7 7
85.2 8
72.5 7
56.8 7
87.4 8
62.2 7
63.2 7
56.1 6
54.4 6
77.2 8
recordings werype 4100; B&K&K) were usedrs of the experirom the groundrded on a field
08Ax).
mage on the peraptured by usinge measurement
100 m, perpenrecordings wer0 pm, based on
ost frequent dur
NOISE
cted from autorelation functionequency characate the psychon noise. Sounduation strengthcalculated using
short-time IACFf the train noiseas 0.5 s, and thof the previound amplitude o
ACF. The longed stronger pitchalized IACF.
rceive the direche subjects can
ACC approache
d train noise ande. Previous stuch as LA50 andlevel are usefu
al areas [6]. Dlimit of rura
0 levels of am-
Table 3. Noise
2 3
70.5 83.3
84.1 88.7
78.5 58.1
71.6 47.6
88.8 91.3
71.6 59.4
72.8 64.2
69.3 54.6
68.0 47.4
83.4 66.7
Pro
e K)
d i-d. d
r-g ts n-re n r-
o-n
c-o-d h, g
F e. e
us of er h.
c-n
es
d u-d
ul e
al
biento70to hhighhigh
Whemosof ruspeeand trainaroumetreffe
Tabof tithensureheignois
It wwereleveincr
Fre
Freqshoweventhe nas w
Peaknoissultsat 1
e leves of rural
4
82.7
87.7
72.4
57.9
89.7
60.6
63.1
59.9
55.3
67.3
oceedings of 20th
nt noise for 10 0 dBA, thus thehis definition. Eher than other hway nearby the
en high speed st sites except fural area can died trains. Eventhe railway wa
n noise showedund 70 to 88 drics such as elct on noise leve
le 3 shows the ime. The LAeq inn decreased as e levels were vghts of the railse barriers and o
was also found te different acc
el increased rapreased.
Figu
quency chara
quency charactwn in Figure 2n though noise noise level in d
well as the low f
ks at high freqse and levels ats of engine noiand 2 kHz bec
soundscape
Sites
5 6
88.0 81.1
93.1 85.6
69.7 75.4
59.2 56.3
96.2 88.6
64.6 61.0
59.4 63.5
54.7 58.7
51.9 57.2
87.8 70.9
h International Co
sites in this stuere are no quieEspecially, nois
sites showinge site.
trains pass byfor site 2. Theristinguish and p
n though the disas the same as d large variatiodBA. This is blevated railwayels.
change in the Lncreased until tthe train went
varied around 8lways were difothers did not.
that increase raording to recorpidly while lev
ure 1. Sound pr
acteristics
teristics of hig2. Train noises
levels are slighdBA is mainly gfrequency comp
quency could bt low frequencyise. In general, cause of rolling
7
73.2
77.0
69.9
56.4
78.5
58.1
62.1
53.9
50.8
69.4
ongress on Acous
udy ranged froet rural soundscse level of site g 70 dBA, bec
y, noise levels refore, residentsperceive the noistance between100 m, levels oons in terms obecause differey and noise bar
LAeq of the sites the train passed
by. Maximum85 to 100 dBAfferent and som
ates of sound prrded sites. At
vels of sites 3 a
ressure levels
gh speed trainshowed a sim
htly different. Fgoverned by hiponent.
be assigned to y are expected peaks are obsnoise from wh
8 9
76.6 69.0
80.9 74.5
69.4 57.5
58.4 46.1
84.7 76.5
54.2 43.4
57.9 46.2
49.4 42.2
47.2 38.2
66.5 49.7
stics, ICA 2010
ICA 2010
om around 42 cae according
2 was much cause of the
increased in s and visitors ise from high
n the receiver of high speed of LAeq, from ent landscape rriers had an
as a function d the receiver, m sound pres-A because the
me sites had
ressure levels site 5, noise
and 9 slowly
n noises are ilar tendency For all trains, gh frequency
aerodynamic to be the re-erved around
heel radiation.
10
74.2
79.9
53.0
45.6
83.5
42.9
44.1
42.3
41.5
46.6
23-27 August
ICA 2010
But in this srolling noisshown in thi
Psychoaco
SQ (sound q
Figure 3 repfluctuation sof critical bathe range oftic results. Tcomponents low frequena measure ofand 200 Hzas a function
Figure
t 2010, Sydney, A
study, aerodynae levels, thus is study.
Figure 2. Freq
oustic charac
quality) metrics
presents the castrength of highand. Loudness wf 16 to 20 Bark This indicates tof high speed
cy component if the sensation . At most sitesn of Bark, but s
(a
(b)
(c) Fluce 3. Analysis re
Australia
amic noise levepeaks at 1 an
quency characte
ctersistics
s
alculated loudneh-speed train nwas dominant acontrary to fre
that the effectstrain noise wouin terms of loudfor modulation
s, roughness shites 3, 4, 10 had
a) Loudness
) Roughness
ctuation strength sults of sound q
els were larger nd 2 kHz were
eristics
ess, roughness,noises as a funat high frequenequency characts of high frequuld be larger thdness. Roughne
n between arounhowed less varid some peaks at
quality metrics
than e not
, and nction ncy in teris-
uency han a ess is nd 20 ation t low
A
Proceedings of
Figure 4.
frequency and because rattle modulation in case of fluctuaences between means that diffeffect on slow m
ACF/IACF par
The 1 and strength respec0.2 ms to 50 mtively, and ten time. When trawere large butdecreased. Thudifferent whenby.
The values of proaching and with 1 could ntors perceive hany specific toincreased whenpitch correspon
Figure 4(c) shIACC were lardecreased and
20th Internationa
(
(c) Analysis result
site 5 showed anoises from tthe range of 2
ation strength, ihigh speed trai
ferent types of lmoving modula
rameters
1 are related tctively. As showms correspondin
sites showed siains were apprt when they paus, the perceiven trains are app
f 1 were less leaving. This in
not be perceivedhigh speed trainonal componentn trains are conding to 1 coul
hows the resultrgest when train
slightly increa
al Congress on A
(a) 1
(b) 1
IACC ts of ACF/IACF
a peak at high fthe railway aff0 and 200 Hz. it is hard to indin noises from landscape metriation of train no
to the pitch swn in Figure 4(ang to 5 kHz andimilar tendencyroaching and leassed by, 1 vald pitch of train
proaching and l
than 0.3 whenndicates that pitd. Therefore, ren noise as simpt at that time. B
oming to the red be perceived
ts of the IACCns were approacased when tho
Acoustics, ICA 20
F parameters
frequency. This fected the sounHowever, in th
dentify the diffethe 10 sites. Thics rarely have aoises.
sensation and a), 1 varied frod 100 Hz, respey as a function eaving, 1 valulues dramatical
n noises would beaving or pass
n trains were atch in accordanesidents and visply noise withoBut the 1 valueceivers, thus thby listeners.
C. The values ching then, muse were leavin
10
3
is nd he er-his an
its om ec-of
ues lly be ed
ap-nce si-
out ues he
of ch
ng.
2
4
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Tlaansinvredn
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Treofoinoapth
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InsomsoEtitrravin
3-27 August 201
Thus, direction rains were apprve the highest s
by in front of lis
The values of IAandscape metricnd 9, the changites are open s
noises from appvalues of sites 2epresents that t
dent on surrounnoise itself.
DISCUSSION
Perception of hibackground noiswere chosen wFigure 5 represhan backgroundrain noise. How
differences betwnoise was maske
Figure
Time history ofecorded sites.
opened, listenerore, noise leveln the figure 6. B
obstacles such appear suddenlyhis case, train n
Fi
SUMMARY A
n the present oundscape with
measurements. oundscape is an
Especially in Koion of opennesrain noises werange of around
values of train nng sites, and th
0, Sydney, Austr
of the noise soroaching and leasubjective diffusteners due to th
ACC showed lacs of recorded
ges of IACC wespace, thus list
proaching and l2, 3 and 7 were the IACC of hinding environm
NS
igh speed trainse levels. For b
with low and hents that train d noise level thuwever, in the cween train noised by road traff
e 5. Effect of ba
f train noises wIf the right an
rs can hear trainl increased slowBut if the right
as mountains any and noise levnoise can produc
igure 6. Effect
AND FUTHE
study, acoush high speed trIt was found
n aggregate of norea, soundscapss. Acoustical re analyzed. Tr70 and 90 dBA
noises were depe perception of
alia
urce is perceivaving. And liste
useness when trhe low IACC va
arge variations asites. In the ca
ere large. This iteners can easieaving trains. Hnot much chan
igh-speed train ments of rural
n noise may habrief comparisohigh backgroun
noise level waus listeners can
case of site 2 wse and backgroufic noise nearby
ackground noise
were also affectnd left sides on noise from fa
wly, for instancet side of the sitend valleys, thenvels would incrce startling effe
of layout of site
ER STUDIES
stical characterrain were inves
that the landnatural and man
pe of rural area characteristics
rain noise leveA. And it was fendent on the laf train noises af
ed clearly wheneners can percerains are passingalues.
according to thase of sites 6, 8is because thosily perceive thHowever, IACCnged. This resul
noise is depenarea as well a
ave an effect onon, sites 9 and 2nd noise levelsas much highe
n easily perceivwith small leveund noise, train
y.
e level
ted by layout oof the site werar away. Thereesite 8 as showne was closed by
n the train wouldrease rapidly. Inects.
es
ristics of rurastigated by fielddscape of ruran-made featureshowed a variaof high speed
els varied in thfound that IACCayout of recordffected by back
Pro
n e-g
e 8, e e C lt
n-as
n 2 s. er e
el n
of e
e-n y d n
al d al es. a-d e C d-k-
grousounlabo
RE1
2
3
4
5
6
oceedings of 20th
und noise levendscape with hioratory experim
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