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Description : Check out this medical presentation on Noise-Induced Hearing Loss, which is titled "Noise-Induced Hearing Loss", to know about the hearing impairment resulting from exposure to high levels of noise.

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Published on : Jul 10, 2021 | Views : 3225 | Downloads : 5

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Slide 1-

Noise-Induced Hearing Loss F. Lortie-Monette Department of Epidemiology and Biostatistics
Slide 2-

Noise-Induced Hearing Loss: Outline Why does it matter? How does it occur? Symptoms? Audiometric testing Prevention
Slide 3-

Causes of Deafness (cf appendix for anatomical sites) Sensorineural loss Conductive loss
Slide 4-

Hearing Loss: Conductive loss Impacted earwax; Ruptured eardrum (blow to head or explosion); Blockage of eustachian tube; Ossicular dysfunction: Dislocation Otitis media or fluid, Otosclerosis
Slide 5-

Hearing Loss: Sensorineural loss Noise Congenital/familial (eg associated with maternal rubella or flu or prenatal medication); Infections (eg measles, mumps, encephalitis, meningitis, cerebral abscess); Ototoxic drugs: streptomycin, gentamicin, neomycin, etc.; diuretics; quinine, ASA Fracture of base of skull; Acoustic neuroma; Ménière’s disease; Presbycusis
Slide 6-

Hearing Loss Noise-induced hearing loss - common Hearing loss from any cause is disabling: interferes with communications/quality of life may represent risks, ie unable to hear warnings
Slide 7-

Noise Social and work related, sources of exposure including: firing of guns, playing in pop groups, listening to amplified music, etc. (cf appendix for examples of noise levels) Explosive noise is more damaging than continuous noise.
Slide 8-

Noise in the Workplace Industries with high #s of exposed workers: mining construction manufacturing
Slide 9-

Noise Exposure at Work: 3 million in Canada exposed to hazardous noise on the job; > 1 million in Ontario; 10-20% of Ontario workforce at risk of NIHL
Slide 10-

What is Noise? Definition: unwanted sound ie unpleasant, interfering or harmful occupational noise: relates to excessive sound and potential harmful effects on human auditory system Basic parameters of noise Frequency: Hertz (Hz) or cps; 20-20,000 Hz Sound pressure: amplitude of sound pressure wave
Slide 11-

Noise Induced Hearing Loss 100% preventable; insidious onset Once acquired, hearing loss is permanent and irreversible Can be acquired from work, home (eg power tools), recreation (loud music, guns, snowmobiles)
Slide 12-

Noise (Cont’d) Hearing damage is related to the total noise dose received at the ear – a product of the noise level and its duration. Unprotected exposure to (100 dB15 minutes) = 8 hours of exposure at 85 dB
Slide 13-

Hazardous Noise Levels 90 dB(A): experienced daily x 40 years  50% chance of 30 dB hearing loss 3 dB “exchange rate” or “trading ratio” = equal energy rule: 3 dB increase in exposure  halving allowed exposure time 85 dB(A) permitted for 8 hr 88 dB(A) - for 4 hr 91 dB(A): - for 2 hr
Slide 14-

General Estimates of Work Related Noise FOR MORE INFO... National Institute for Occupational Safety and Health (NIOSH) www.cdc.gov/niosh
Slide 15-

Effects of Noise 2nd most common sensorineural hearing loss, after presbycusis Sounds exert shearing force of cilia of hear cells lining basilar membrane of cochlea when excessive  metabolic overload, cellular damage and death damaged cochlea cannot be repaired once removed from damaging noise, no further progression of NIHL
Slide 16-

This is your ear. This is your ear on noise. Any questions?
Slide 17-

Effects of Noise on Hearing Temporary threshold shift (TTS) temporary hearing decrease following noise exposure: resolves gradually after removal from noise Permanent threshold shift (PTS)) irreversible hearing decrease following high or repeated exposure
Slide 18-

Noise Induced Hearing Loss Characterized by insidious onset: Gradual loss of clarity in perceived speech, often attributed to inattention or to others not speaking clearly; difficulty in hearing high-frequency sounds of speech (consonants s,f,k,t,sh) Difficulty in understanding others in a crowd, often presumed to be due to competition with background noise. High pitch tinnitus, initially intermittent, becomes continuous in up to 20% of cases, and can be a presenting symptom.
Slide 19-

Prevention Screening questions for excessive noise exposure during routine exam/health maintenance visits: “Are you exposed to excessive noise in your workplace or through music or hobbies?” “Do you often have to shout to hear someone at arm’s length because it’s so noisy around you?”
Slide 20-

Prevention Screening questions for excessive noise exposure during routine exam/health maintenance visits: Ask about specific sources of noise Ask about hearing protection: “how often do you use earplugs, earmuffs, etc?
Slide 21-

Prevention (Cont’d) A general rule of thumb is: if you need to shout to communicate effectively with someone within three feet, or if after noise exposure your ears feel blocked, or you experience temporary tinnitus, the noise is harmful.
Slide 22-

Hearing Impairment Questions: “Do you have any difficulty with understanding speech in noisy environments?” “Is your hearing not as good as it was 10 years ago?” “Have family members noticed a problem with your hearing?
Slide 23-

Audiometric Testing Hearing loss: measured by determining auditory threshold (sensitivity) at various frequencies No loud noise exposure for at least 16 hours prior to test, to avoid temporary lowering of hearing threshold. Learning effect up to 10-15 dB means that the second ear may test better than the first, or that the second hearing test may be better than the first one.
Slide 24-

A Few Pointers on Interpreting Audiometric Testing A loss of less than 20 dB in all frequencies can be considered normal. A similar reduction in all frequencies or one where the threshold improves in the higher frequencies = conductive loss. A notch in the region of 1-3 kHz = familial cause of hearing loss. Presbycusis produces a smooth pattern of increasing loss in higher frequencies; these changes increase progressively.
Slide 25-

Audiometric Characteristics of Noise Induced Hearing Loss Bilateral notch in hearing threshold at 3, 4, or 6 kHz with recovery of 8 kHz (classic occurs at 4 kHz); Progressive deepening and widening of notch with increasing exposure to noise; Notch due to shooting is narrow and asymmetrical (in right handed people, it is deeper on left side because right ear is protected by gun stock); Action levels: worsening of 10 dB(A) at 2,3,4 Hz vs baseline - worker should be notified.
Slide 26-

Diagnosis of NIHL Typical pattern of NIHL on audiometry History of noise exposure Absence of other conditions causing hearing loss major diagnostic problems: hearing loss associated with presbycusis or ototoxic agents determining degree of impairment due to aging
Slide 27-

Hearing Loss Among Male Carpenters as a Function of Age
Slide 28-

The Average 25 Year Old Carpenter Has 50 Year Old Ears!
Slide 29-

Non-Noise Exposed Worker Noise Exposed Workers Percent of People With Tinnitus
Slide 30-

Etiological paradigm of hearing loss in an industrial population Occupational factors: noise vibration + noise industrial ototoxic exp (eg solvents) industrial head injury/acoustic trauma Extra-occup factors: age extra-occupational noise disease ototoxic drugs non-occupational trauma
Slide 31-

Presbycusis Literally means “old man’s hearing” eardrum loses its elasticity and the joints of the ossicular bones stiffen affects as many as 60% of people over 65 affects basically all over 80
Slide 32-

normal hearing Hearing by Age
Slide 33-

Hearing Levels in 60 Year Old Males as a Function of Noise Exposure
Slide 34-

Prevention of NIHL: Engineering control Ear protectors (sounds attenuated to about 80 decibels - more would be associated with social isolation). Protection must be used continuously.
Slide 35-

Prevention of NIHL When workers are or may be exposed to noise above 85 dB, employers must: Measure the daily noise exposure Identify significant sources of noise Change the equipment to reduce noise (eg absorbent materials on walls or ceilings) Implement hearing conservation program Provide hearing protection
Slide 36-

Prevention of NIHL Two main types of hearing protection: earplugs and earmuffs (follow CSA Standard Z94.2-94, Hearing protectors)
Slide 37-

Prevention of NIHL If using earmuffs: Replace muffs when hard or cracked Keep them clean with mild soap and water If using earplugs: Plug must make good seal in ear canal Discard compressible plugs at end of work shift Wash reusable earplug once a week with mild soap and water
Slide 38-

People have MANY reasons for not using hearing protectors. (AKA: You can lead a person to hearing protectors, but you can’t get him/her to wear them.) THE FOUR C’s Comfort Convenience Cost Communications / hear important sounds THERE ARE OVER 200 DIFFERENT HEARING PROTECTORS. EVERYONE CAN FIND A PROTECTOR THAT MEETS THEIR NEEDS. THE BEST HEARING PROTECTOR IS THE ONE THAT’S WORN!
Slide 39-

Prevention (Cont’d) One should not be exposed to 110 dB for greater than 0.5 hours per day without ear protection. At 1,000 dBa, a reliable ear plug (premolded, formable [foam, fiberglass, silicone, etc.] or custom molded), should afford approximately 20 dB hearing protection attenuation an an ear muff approximately 30 dB. When used together, they provide up to 40 dB attenuation.
Slide 40-

Effect of inconsistent use of hearing protection on the amount of effective noise reduction
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Slide 42-

Factors Affecting Behavioral Change: Individual Level Knowledge/beliefs Attitudes/values Stage of change Decisional balance Self-efficacy Organizational Level Norms- safety culture Union and management priorities Training Environmental support
Slide 43-

Does this touchy-feely stuff work? You bet it does!
Slide 44-

Wise-Ears Web Links www.nih.gov/nidcd/health/wise/ www.cdc.gov/niosh/noise www.aearo.com www.howardleight.com www.hearnet.com www.hearingconservation.org
Slide 45-

Appendix:
Slide 46-

External Ear: causes of deafness Wax or foreign body in the canal Swelling of canal (inflammation or infection)
Slide 47-

Middle Ear Significant scarring or perforation of drum Eustachian tube dysfunction Infections (e.g. otitis media) Dislocations or adhesions of ossicular chain Otosclerosis (staples immobilized in oval window).
Slide 48-

Inner Ear Noise Presbycusis Heredity Ototoxic drugs Infections (e.g. meningitis) Ménière’s disease Trauma
Slide 49-

Cranial Nerve VIII and Central Auditory Pathways Presbycusis Trauma Infections Ototoxic drugs Tumors
Slide 50-

Common Sounds Common Sounds Countryside with rustling leaves Normal conversation Decibel Level 20-50 dBa 50-70 dBa Effect Peaceful and quiet Comfortable
Slide 51-

Common Sounds (Cont’d) Common Sounds City traffic Hair dryer Inside car Decibel Level 70-80 dBa Effect Intrusive This kind of noise makes it hard to hear someone when you are talking on the telephone.
Slide 52-

Common Sounds (Cont’d) Common Sounds Lawnmowers Subway Busy restaurant or kitchen Decibel Level 75-90 dBa Effect Annoying This kind of noise makes it hard to carry on a conversation. You can have hearing damage from this level of noise over time.
Slide 53-

Common Sounds (Cont’d) Common Sounds Power tools Walkman Motorcycles Snowmobiles Manufacturing plant hydraulic press, punch press Pneumatic drill Decibel Level 90-100 dBa Effect Very Annoying At this level, your hearing is being damaged.
Slide 54-

Common Sounds (Cont’d) Common Sounds Chain saw Air gun Boiler room Sandblasting Decibel Level 100-120 dBa Effect Being exposed to this kind of noise for more than 1 minute exposes you to hearing damage.
Slide 55-

Common Sounds (Cont’d) Common Sounds Jet takeoff Gun shot Decibel Level 120-140 dBa Effect At this level of noise, you reach the upper limit of pain to the ear.