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.
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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?
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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
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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
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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.
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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)
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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
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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
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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).
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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)
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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
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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
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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’
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