Transpor Sedimen dan Dinamika Pantai Explicit Formulation of The Sields Diagrams For Incipient Motion of Sediment. Zhixian Cao, Gareth Pender, and Jiang Meng (2006) Dipresentasikan oleh : Fernandus Brilianto Gautama – 12909005 Reza Triafsa Gauss – 12909023 Astrini Nurul Sentanu – 12910016 PROGRAM STUDI OSEANOGRAFI FAKULTAS ILMU DAN TEKNOLOGI KEBUMIAN INSTITUT TEKNOLOGI BANDUNG - 2013 Sebagai Penilaian Ujian Tengah Semester I Tahun 2013/2014
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• A sound barrier is a solid structure that intercepts thedirect sound path from a sound source to a receiver.
• It reduces the sound pressurelevel within its shadow zone.
Barrier Fundamentals
THE EFFECT OF A BARRIER ON SOUND WAVES
BARRIER
BRIGHT ZONESOUND W
AVE
REFLECTEDSOURCE RECEIVER
STRAIGHT PATH
DIFFRACTED PATH
SHADOW ZONE
TRANSMITTED
2
0
3
1
4
5
6 DE
CIB
EL
S O
F N
OIS
E R
ED
UC
TIO
N
Typical Noise Barrier Wall
Fundamental Issues
• How high does the barrier have to be?
• How close should the barrier beto the equipment?
• How much sound attenuation will we get from the barrier?
Barrier Attenuation
• Based on mathematics involvingFresnel integrals (borrowed fromoptical diffraction theory).
• The theory agrees well with measurements.
• Tables and graphs are availablefor practical use.
Path Length Difference
• PLD is determined from basic geometry.
• Affected by barrier height and location.
• Also affected by source and receiver heights.
• A larger PLD will result in higherattenuation.
Path Length Difference
5 ft 5 ft
A = 6.4 ft
B = 5.1 ft
D = 10.4 ft
POSITION 1: PLD = A + B - D = 1.1 ft
SOURCE
RECEIVER
Path Length Difference
1 ft 9 ft
A =
4.1
ft
B = 9.1 ft
D = 10.4 ft
POSITION 2: PLD = A + B - D = 2.8 ft
SOURCE
RECEIVER
INSERTION LOSS VALUES FOR AN IDEAL SOLID BARRIERINSERTION LOSS VALUES FOR AN IDEAL SOLID BARRIER
Path-LengthDifference, ft 31 63 125 250 500 1000 2000 4000
0.01
0.02
0.05
0.1
0.2
0.5
1.0
2.0
5.0
10.0
20.0
50.0
5
5
5
5
5
6
7
8
10
12
15
18
5
5
5
5
5
7
8
10
12
15
18
20
5
5
5
5
6
9
10
12
14
17
20
23
5
5
5
6
8
10
12
14
17
20
22
24
5
5
6
7
9
12
14
17
20
22
23
24
6
6
7
9
11
15
17
20
22
23
24
24
7
8
9
11
13
18
20
22
23
24
24
24
8
9
10
13
16
20
22
23
24
24
24
24
Insertion Loss, dB
Octave Band Center Frequency, Hz
Barrier Attenuation
• High frequencies are attenuatedmore effectively than low frequencies.
• The maximum theoretical limit for barrier attenuation is 24 dB.
• The actual attenuation will always be less due to practical limitations.
Attenuation WorksheetSound Barrier Attenuation WorksheetSource: Return air intake louvreReceiver: Second floor bedroom window at 100 feet distance (30 m)