Properties of noise?

Kebisingan Industri
Objective
Penyebab kehilangan/gangguan
pendengaran adalah:
z Kebisingan industri
z Luka pada telinga akibat ledakan, shock
pukulan pada kepala dan benda asing atau
infeksi pada telinga.
?
Inside NOISE
z What is noise?
– Definition, energy conducted and sensed, properties:
intensity/pressure, frequency, exposure,
z Why unwanted?
– Health Effect, age, psychological: annoyed, concentration,
rest/relax problem, communication annoyance,
physiological: blood, heart, hearing loss, nausea, muscle
control, acoustic trauma (permanent) vs temporary,
z Who are susceptible?
– Esp. Industrial workers, determining factors: sensitivity,
age,
z How to evaluate & control?
What is noise?
Definisi:
z Suara-suara yang tidak dikehendaki (for Who?
Why?)
z Suara: sensasi yang diterima telinga sebagai
akibat fluktuasi tekanan udara terhadap tekanan
udara yang stabil.
z Telinga akan merespons fluktuasi-fluktuasi kecil
tersebut dengan sensitivitas yang sangat besar.
z Bising juga diartikan vibrasi/energy yang
dikonduksikan dalam media udara, cairan,
padatan, tidak tampak dan dapat memasuki telinga
serta menimbulkan sensasi pada alat dengar
Properties of noise?
1
Jenis Bising
z Tergantung pada durasi dan frekuensi
z Steady wide band noise, bising yang meliputi suatu
jelajah frekuensi yang lebar (bising dalam ruang
mesin)
z Steady narrow band noise, bising dari sebagian besar
energi bunyi yang terpusat pada beberapa frekuensi
saja, contoh gergaji bundar.
z Impact noise, kejutan singkat berulang, contoh
riveting
z Intermitten noise, bising terputus, contoh lalu lintas
pesawat
Contoh…
Karakteristik bising
1.
Intensitas/tekanan (sound
pressure/intensity)
2. Frekuensi
3. Durasi eksposur terhadap bising
Ketiga karakteristik diperlukan karena:
z Semakin keras suara, semakin tinggi
intensitasnya
z Frekuensi tinggi lebih berbahaya terhadap
kemampuan dengar. Telinga manusia lebih
sensitif terhadap frekuensi tinggi
z Semakin lama durasi eksposur semakin
besar kerusakan pada mekanisme
pendengaran
Intensitas
z Laju aliran energi tiap satuan luas yang dinyatakan
dalam desibell (dB) – Alexander Graham Bellz dB adalah merupakan satuan yang dihasilkan dari
perhitungan yang membandingkan suatu tekanan
suara yang terukur terhadap suatu tekanan acuan
(sebesar 0,0002 dyne/cm2).
z B = log (int.terukur/int.acuan) untuk mendapatkan
angka yang lebih akurat ditentukan dengan angka
kelipatan 10 (desi)
z Intensity level dB=10 Log (IT/IA)
z Sound pressure level (tekanan bunyi) = 20 log
(IT/IA), karena intensitas sebanding dengan kuadrat
tekanan bunyi.
Tekanan = Sound Pressure
z Manusia dapar mendengar suara pada
tekanan antara 0,0002 dynes/cm2 (ambang
dengar/threshold of hearing) sampai 2000
dynes/cm2 Æ range besar sehingga satuan
yang dipakai dB (decibel): logaritmik
z Dinyatakan dalam decibel (dB) yang
dilengkapi skala A, B, dan C
Æ sesuai dengan berbagai kegunaan
z Skala A digunakan karena merupakan
response yang paling cocok dengan telinga
manusia (peka terhadap frekuensi tinggi)
z Skala B dan C untuk evaluasi kebisingan
mesin, dan cocok untuk kebisingan frekuensi
rendah
z
z
z
z
z
z
Ruang kelas: ?dB
Rumah
Restauran
Berbisik
Berteriak
Jet plane
2
The decibel
The decibel
SOUND INTENSITY
SOUND SOURCE
z
LINEAR UNITS
Bel
LOGARITHMIC UNITS
Decibel
Lowest limit of hearing
1
0
0
Rustling leaf
10
1
10
Quiet farm setting
100
2
20
Whisper (5 feet)
1,000
3
30
Dripping faucet, quite office
10,000
4
40
Low conversation, residence
100,000
5
50
Ordinary conversation
1,000,000
6
60
Idling car
10,000,000
7
70
Silenced compressor, very noisy restaurant
100,000,000
8
80
Backhoe
1,000,000,000
9
90
Unsilenced compressor
10,000,000,000
10
100
Rock dril, woodworking
100,000,000,000
11
110
Pile driver*
1,000,000,000,000
12
120
Rivet gun*
10,000,000,000,000
13
130
Explosive-actuated tool*, jet plane
100,000,000,000,000
14
140
z dB = 10 log10 (I1/I0)
dB = 20 log10 (P1/P0)
SP (microbar)
0,0002
0,002
I = Intensitas
P= Tekanan = 0,0002
dynes/cm2
SPL (dB)
0
20
Ratio Intensitas
100
102
Jadi bila SP berubah 10x, maka dB bertambah ? x
*Intermittent or "impulse" sound
Source: Construction Safety Association of Ontario, Hearing Protection for the Construction Industry, 1985, page 3
Satuan (Konversi)
Pressure
Sound intensities
Pa
Bel (B) Decibel (dB)
Threshold of hearing
0,00002
0
0
Quiet office
0,002
4
40
Ringing alarm clock at 1 m
0,2
8
80
Ship's engine room
20
12
120
Turbo jet engine
2000
16
160
z 1bar=105Pa=105N/m2
z
=105.105dyne/104cm2
z
=106dyne/cm2 atau
z 1microbar = 1 dyne/cm2
Sumber > 1…..
Sumber > 1….. (Contoh)
z dB=L=20 log(P1/P2)=10 log(P1/P2)2
z L/10= log(P1/P2)2
z 10L/10= 10log(P1/P2)^2=(P1/P2)2
z =10 log (Σ10Li/10)
z L=10 log(P1/P2)2
z =10 log 10L/10 (satu sumber)
z =10 log (Σ10Li/10)
z =10 log (10L1/10+L2/10+…)
(banyak sumber)
z =10 log
(10L1/10+L2/10+…)
Perbedaan
antara sumber
bunyi
ΣdBA yang turun
ditambah ke
bunyi terbesar
0
3,0
1
2,6
2
2,1
3
1,8
4
1,5
5
1,2
6
1,0
7
0,8
8
0,6
10
0,4
12
0,3
14
0,2
16
0,1
3
Frekuensi
z Adalah jumlah getaran dalam tekanan
suara per satuan waktu (Hertz atau
cycle per detik), frekuensi dipengaruhi
ukuran, bentuk dan pergerakan
sumber, pendengaran normal orang
dewasa dapat menangkap bunyi dengan
frekuensi 20-15.000 Hz.
Why unwanted?
Health Effect, age, psychological:
annoyed, concentration, rest/relax
problem, communication annoyance,
physiological: blood, heart, hearing loss,
nausea, muscle control, acoustic trauma
(permanent) vs temporary,
Interference with communication by speech
z When background or ambient noise levels are sufficiently
high enough, the background noise can mask the sound
levels of speech that wish to be heard.
Frekuensi
z Dibagi dalam 8 octaf (octave bands), 37.5, 75, 150,
300, 600, 1200, 2400, 4800, 9600 Hz
z Telinga manusia bereaksi beda terhadap berbagai
frekuensi
z Kebisingan ‘rata-rata’ mencakup seluruh taraf
kebisingan dari setiap frekuensi Æ dihitung Leq
Leq = ekuivalen noise level/ekuivalen energi level
Leq = 10 log10 (Σ 10 Lpi/10)
Efek bising pada manusia
z Psikologis, terkejut, mengganggu dan
memutuskan konsentrasi, tidur dan
saat istirahat
z Fisiologis, seperti menaikkan tekanan
darah dan detak jantung, mengurangi
ketajaman pendengaran, sakit telinga,
mual, kendali otot terganggu, dll.
z Gangguan komunikasi yang
mempengaruhi kenyamanan kerja
dan keselamatan.
Mechanics of hearing
z
z Restaurants can often be classic examples of excessive
noise interference due to lack of sufficient quality or quantity
of sound absorbing materials that prevent excessive noise
buildup.
z Diners have to speak louder and louder to be heard and in
doing so compete with one another, thereby increasing the
sound levels to even greater levels. Appropriate acoustical
treatment will prevent the reflected noise buildup and
significantly reduce the necessity for diners to speak louder to
enjoy conversations with one another.
4
Mekanisme pendengaran
Mekanisme pendengaran
• Terdiri dari 3 bagian: telinga
luar (daun telinga sampai
membran timpani)
Æmeneruskan gelombang ke
telinga tengah
• Telinga tengah: membran
timpani (yang melekat pada 3
tulang kecil sampai
membrana ovale) Æ getaran
diteruskan
• Telinga dalam: tube berspiral
seperti rumah siput berisi
cairan Æ cairan bervibrasi Æ
stimulasi rambut sel Æ impuls
syaraf otak
Pengukuran bising
z Pemaparan pada suara tinggi dan
periode/durasi yang lama akan
menyebabkan sel syaraf pendengar dan
rambut pada corti over aktif sehingga
menimbulkan kehilangan pendengaran
permanen
Audiometric test
z
Untuk mengevaluasi akibat pemaparan
terhadap kehilangan pendengaran,
kenyamanan, interferensi komunikasi
dan mengumpulkan informasi untuk
pengontrolan.
Audiometric test
z
Audiometric test
Current OSHA Standards
z
•1926.52
Occupational Noise Exposure
•TABLE D-2 - PERMISSIBLE NOISE EXPOSURES
Duration per day, hours
Sound Level dBA slow response
8
90
6
92
4
95
3
97
2
100
1 1/2
102
1
105
1/2
110
1/4 or less
115
5
z
Pneumatic chip
hammer
103-113
Crane
90-96
Jackhammer
102-111
Hammer
87-95
Concrete joint
cutter
99-102
Gradeall
87-94
Skilsaw
88-102
Front-end loader
86-94
Stud welder
101
Backhoe
84-93
Bulldozer
93-96
Garbage disposal
(at 3 ft.)
80
Earth Tamper
90-96
Vacuum cleaner
70
How Does Excessive Noise
Damage Your Ears?
z Microscopic hair cells of the cochlea are exposed to
intense noise over time
z Hair cells become fatigued and less responsive, losing
their ability to recover.
z Damage becomes permanent resulting in noise-induced
permanent threshold shift.
z Risk of Hearing Loss
z Estimated Risk of Incurring Material Hearing Impairment
as a Function of Average Daily Noise Exposure Over a
40-year Working Lifetime (source: NIOSH)
z Average Exposure 90 dBA 29%
z Average Exposure 85 dBA 15%
z Average Exposure 80 dBA 3%
What Is The Purpose of Having a
Hearing
Test on a Regular Basis?
z
Ketulian
= berkurangnya
ketajaman pendengaran
dibanding/terhadap orang normal (15 dB)/ gol usia
• Ada 2 macam:
- permanen: karena penyakit, usia tua, obat, trauma, dan
kebisingan
- temporer: akibat ekposur bising, dapat pulih setelah
istirahat beberapa saat tergantung keparahan
• Ketulian temporer akan menjadi permanen bila terus
terekpos bising (dari rumah, tempat umum, rekreasi,
musik, industri, dll.)
• Secara mekanisme: ketulian ada 2:
- konduktif: peralatan konduksi suara rusak akibat
trauma atau sakit
- sensorinueral: akibat persyarafan pendengaran rusak
FIGURE 1. Audiogram findings in the patient in
case 1.
z An audiometric testing program is used to track
your ability to hear over time.
– Baseline and annual
z Test records provide the only data that can be
used to determine whether the program is
preventing noise-induced permanent threshold
shifts. It is an integral part of the hearing
conservation program.
z Case Study 1. Teenage Girl
From the American Academy of Family
Physicians website, Rabinowitz article
The area below the curves represents sound levels that the patient could still hear.
(X = left ear; O = right ear)
6
Case Study 1 Conclusion
Case Study 2 Factory Worker Age 55
z "Temporary threshold shift" example
z Common in persons exposed to high
noise
z Represents transient hair cell
dysfunction
z Complete recovery can occur
z Repeated episodes of such shifts
causes permanent threshold shifts
because hair cells in the cochlea are
progressively lost.
Case Study 2 Conclusion
Carpenter Hearing Losses by Age
z Noise Induced Hearing Loss
– Speech discrimination and social function
interference
– Difficulty in perceiving and differentiating consonant
sounds
– Sounds such as a baby crying or a distant telephone
ringing, may not be heard at all.
z Tinnitus
– Common symptom of noise overexposure
– Further interferes with hearing acuity, sleep and
concentration.
z These impairments have been associated with
depression and an increased risk of accidents.
Pengukuran kebisingan
• Mengukur overall level Æ sound level
meter (satuan dBA)
• Mengukur kebisingan pada setiap level
frekuensi Æ SLM dengan frequency
analyzer
• Penentuan eksposur kebisingan pada
pekerja Æ noise dosimeter (satuan dBA)
NOISE
MEASUREMENT
KIT
NOISE KALIBRATOR
SOUND
LEVEL
METER
NOISE DOSIMETER
7
PENGUKURAN PADA
PEKERJA
DOSEBADGER
Damage risk criteria
Noise control
z Variation in individual susceptibility
z The total energy of the sound
z The frequency distribution of the sound
z Other characteristics of the noise
exposure, such as whether it is
continuous, intermittent, or made up of a
series of impacts
z The total daily time of exposure
z The length of employment in the noise
environment.
z A source radiating sound energy
z A path along which the sound
energy travels
z A receiver such as the human ear
Pengendalian kebisingan
•Cara teknis:
SUMBER
SUMBER
PATHW AY/MEDIA
PENERIMA/RECEIVER
Pengendalian dilakukan di 3 bagian: SUMBER, RUANG
ANTARA sumber dan penerima/pekerja, pada
PENERIMA/PEKERJA
Urutan pengendalian paling efektif:
• Kurangi/hilangkan sumber bising
• Pengendalian pathway: jarak diperjauh dengan
perisai/isolator/automatisasi
• Perlindungan penerima dari bising (APD)
PATHWAY
PENERIMA
Substitusi
Absorpsi/damping
Isolasi pekerja
Insulasi sumber
Perisai
Reduksi waktu
Perpanjang jarak
APD
•Cara medis:
Pemeriksaan ketajaman pendengaran secara periodik
Penempatan pekerja sesuai dengan kepekaan thd bising
Monitor ketulian temporer
•Cara manajemen:
Reduksi waktu eksposur
Diklat pemakaian dan pemeliharaan APD
8
Noise control
Noise control
z Source: modification or
redesigning of the source.
z Noise can be controlled at the source, along the
path or at the worker. At the source, equipment
may be replaced by quieter models, or less
noisy work procedures can be adopted. In
general, less friction and vibration mean less
noise. Maintenance procedures such as
lubrication may sometimes reduce noise by
reducing friction. Equipment can sometimes be
modified to reduce the amount of noise that is
generated. Sound-absorbing material may be
attached to the noise source. Or the frequency
of the noise may be shifted to one that is less
hazardous.
–
–
The modification of compressed air jets for parts
ejection, to reduce noise by altering the jet flow.
Multiple-opening air ejection nozzel: less noise than
single-opening.
Noise control
z Noise can often be controlled along the
path to the worker with the use of soundabsorbing paneling on walls or ceilings,
and enclosures around noisy machinery.
z Controls at the worker include both
administrative controls and personal
protective equipment.
– Administrative controls modify how the work
is carried out.
– The time employees spend in noisy areas
may be reduced.
– Workers in noisy areas may be rotated to
less noisy areas.
As the distance from the noise source increases, the
pressure (or intensity) of the noise decreases faster than its
sound level.
Noise control
Insulation of the workers
z Noisy operations may be conducted
outside normal working hours to
reduce the number of people
exposed.
z Where noise exposures cannot be
reduced by other methods, hearing
protection is required. This
includes ear plugs and ear muffs.
z A separate noise insulated room
provides effective control (up to 30
dB noise reduction).
9
Machine insulation
Control of noise by absorption
z Machine: on floors and walls
Ævibrate themÆsound radiation
proper use of machine mountings
insulates the machine and reduce
the transmission of vibration
z Travels out in all direction
z When encounter wallsÆreflected
z Total noise exposure within the
room = direct + reflected noise
z Application of sound absorption
material (However, limited: no
effect on direct noise).
Reduction of exposure time
Personal protection against noise
z Limiting the total daily exposure
reduces the noise hazard.
z See TLV
z Many operations cannot be quieted
by engineering methods.
z Therefore Æ protection: ear plugs
z Properly worn: 25 – 400 dB
protection
z Degree of discomfort :[ Æ employee
education is adequate
Example….
Alat ukur
z Durasi tingkat bising yang
diijinkan dapat dilihat dari tabel
di bawah ini:
z Kebisingan yang terukur di
suatu area adalah 90 dB selama
2 jam sehari, 97 dB selama 2
jam, dan sisa 4 jam berikutnya
terdapat variasi tingkat bising
secara bergantian 95 dB selama
10 menit dan 80 dB selama 10
menit. Tentukan apakah tingkat
kebisingan yang terukur masih
dalam batas yang diijinkan atau
tidak.
Durasi per hari
Tingkat bising
8
6
4
3
2
1,5
1
¾
½
¼
90
92
95
97
100
102
105
107
110
115
z Sound level meter, mencatat keseluruhan suara
yang dihasilkan tanpa memperhatikan
frekuensi yang berhubungan dengan bising
total (30-130 d) – (20-20.000Hz)
z Sound level meter dengan octave band
analyzer, mengukur level bising pada berbagai
batas oktaf di atas range pendengaran manusia
dengan mempergunakan filter menurut oktaf
yang diinginkan (narrow band analyzers untuk
spektrum sempit 2-200 Hz)
10
Faktor-faktor yang mempengaruhi
bising
Waktu pemaparan vs dB
Waktu pemaparan (jam)
dB
8
6
4
2
1,5
1
0,5
<0,25
90
92
95
100
102
105
110
115
z Tipe bising: menerus dan terputus
z Lokasi pekerja
z Waktu kerja
(Sumber: FHI)
Kontrol bising
z Sumber energi suara (modifikasi sumber)
z Pengaturan media (isolasi/insulasi, perbesar jarak)
z Penerima (pekerja pada tempat tertutup, pelindung
telinga, pengaturan waktu kerja)
(Gambar: 3 komponen pengendalian bising)
Steps aiming to control noise at
work
z Assess risks to develop a noise control
plan
z Reduce risks for all employees
z Investigate and implement good practice
for control of noise
z Prioritise noise control measures
z Use hearing protection for residual risks
z Carry out a noise dosimetry program to
check the effectiveness of noise control
measures
Some simple noise control
techniques
z Application of damping material to
chutes, hoppers, machine guards etc.,
can give a 5-25 dB reduction in the noise
radiated
z Cabin internal noise can be reduced by
10-12 dB by applying damping pads and
sound barrier mats to floor and engine
bulkhead
z Reduce fan speed by 30% to achieve a
noise reduction of 8 dB
BARRIER-BARIER ATAU PANEL
11
Noise control can be complex
ISOLASI PEKERJA/MESIN DI TEMPAT BISING
Engage employees in
process
Use noise control
consultants to help
solve your problems
if complex
BAHAN ABSORBER
BAHAN BARRIER
Hearing protectors
z Selected for protection, user preference
and work activity
z Guard against over-protection — isolation
can lead to under-use and safety risks
z Require information, instruction,
training, supervision and motivation
z Will only protect if worn all the time and
properly
Class and specification of
hearing protectors
Class
May be used up to this
noise exposure level
10 to 13
1
90 dB(A)
14 to 17
2
95 dB(A)
18 to 21
3
100 dB(A)
22 to 25
4
105 dB(A)
26 or
greater
5
110 dB(A)
SLC80
Rating hearing protectors
The sound level conversion (SLC80 ) rating of a hearing
protector, ear plugs or headset is a simple number and class
rating that is derived from a test procedure as outlined in the
Australian/New Zealand Standard AS/NZS 1270:2002
Ear plugs
Properly fitted
Wrongly fitted
12
Reduction in protection provided by
hearing protectors with decreased
wearing time
Ear muffs
Proper clamping force
Example:
Effectiveness of
wearing an ear
muff with a rating
of 30 dB for an
exposure time of
one hour
NAB Kebisingan di lingkungan kerja
Effective
attenuation
60 minutes
30 dB
55 minutes
11 dB
50 minutes
8 dB
45 minutes
6 dB
Kebisingan dari 2 sumber
INDONESIA Permen 51/1999
t (eksposur) jam
dB(A)
8
90
6
92
4
95
3
97
2
100
1,5
102
1
105
0,5
110
<0,25
115
kebisingan impulsif < 140 dB
t
dBA
8
85
4
88
2
91
1
94
30 mnt
97
15 mnt
100
7,5 mnt
103
3,75 mnt
106
1,88 mnt
109
dst
dilarang > 140 dB
Decibel yang ditambahkan pada
tingkat kebisingan lebih tinggi
USA (TLV ACGHI)
Wear time
Worn-out head band
3
2,5
2
Perbedaan (dB)
0 atau 1
Tambah pada yg lebih
tinggi
3
2 atau 3
2
4–9
1
10+
0
1,5
1
0,5
2
4
6
8
10
12
14
Perbedaan antara 2 tingkat bising, dB(A)
Our challenge
Away from …
z Noise assessment as the end point
z Reliance on hearing protection
Towards …
z Control of noise risks through prioritised
action plans
z Introducing equipment with good noise
and vibration characteristics – ‘Buy
Quiet’
13