1. INDUSTRIAL NOISE …the nature & effects of exposure to excessive noise…..I SAID, THE NATURE & EFFECTS OF EXPOSURE TO EXCESSIVE NOISE

2. What is sound? l “… any pressure variation that the human ear can detect” l “…..sensation produced through the organs of hearing usually by vibrations transmitted in a material medium, commonly air.” l If a tree falls in a forest… l Noise = unwanted sound!

3. What is the need? l Estimates show that 16.9% of the working population are employed in jobs where noise levels exceed 85 dB. l It is estimated that 1.7 million workers in the US between 50 and 59 years of age have compensable noise-induced hearing loss. The potential cost to industry could exceed $500 million.

4. Properties of Sound l WAVELENGTH l FREQUENCY l PITCH l INTENSITY l PRESSURE

5. HOW DO WE HEAR? l OUTER EAR (funnels waves to eardrum) l MIDDLE EAR (transfers sound energy from outer to inner ear) l INNER EAR (has receptors for hearing and position sense)

6. THE COCHLEA l Sensory organ for hearing l Organ of Corti l Frequency is a function of position; i.e.., hairs at base respond to high frequencies

7. EAR’S NATURAL DEFENSES l Secretion of wax l Hairs in outer ear l Bent ear canal l Contractile muscle in eardrum/middle ear l Air-filled middle ear

8. NON-NOISE-INDUCED HEARING LOSS l Physical blockage of auditory canal l Traumatic damage l Disease damage l Hereditary or prenatal damage l Drug-induced damage l Presbycusis

9. NOISE-INDUCED DAMAGE l Physiological –Temporary & permanent threshold shifts –Acoustic trauma vs. noise- induced hearing loss l Psychological l Cardiovascular l Speech interference l Other

10. The effect that excessive noise has on an individual’s hearing... l Noise intensity (sound pressure level) l Frequencies/pitch l Time/type relationship (continuous/intermittent) l Duration of exposure episodes l Total work duration l Individual susceptibilities

11. Common sounds in decibels l Sound is measured in decibels (dB) l 10 dB – human breathing, rustle of leaves l 20 dB – average whisper l 30 dB – average residence w/o stereo playing l 50 dB – average office l 60 dB – near freeway auto traffic l 80 dB – school cafeteria l 90 dB – noise factory, noisy urban street l 100 dB – loud horns at 10 feet away l 110 dB – accelerating motorcycle at a few feet away l 120 dB – hard rock band l 130 dB – threshold of pain l 140 dB – near jet engine

12. Common industries… l Construction l Mining l Agriculture/forestry l Manufacturing –Textile, food, lumber, furniture, paper, printing, chemicals, petroleum, leather, metal, machinery, electronics etc. l Services –Auto repair, other repair services, etc. l Transportation –Passenger transit, trucking and warehousing, transportation by air, electric, gas, and sanitary services

13. Steps in identification l Preliminary noise survey –Carried out at work areas where it is difficult to communicate in normal tones –When workers notice that sounds are muffled or they develop ringing in their ears l Detailed noise survey –How noisy is each work area? –What equipment or process is generating noise? –Which employees are exposed to the noise? –How long are they exposed?

14. TLVs and PELs l TLV’s for Noise –8 hrs 85 dB –4 hrs88 dB –2 hrs91 dB –1 hr94 dB –.5 hr97 dB –.25 hr100 dB l PELs for Noise –8 hrs90 dB –4 hrs95 dB –2 hrs100 dB –1 hr105 dB –.5 hr110 dB –.25 hr115 dB

15. Impact Noise l Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level

16. Permissible Exposure Levels l 90 dB is established PEL l However, at 85 dB one must implement an effective hearing conservation program

17. OSHA Hearing Conservation Program (29 CFR 1910.95) l Noise monitoring l Audiometric testing program l Employee follow-up and referral l Hearing protection l Employee training l Recordkeeping