Occupational hearing loss and prevention

Boiler makers and gunners were the predecessors

1510-1590

1873

self inflicted hearing loss

Rock Musician Pete Townshead--- prompted by his partial deafness and Tinnitus –formation ---H E A R (Hearing Education and Awareness for Rockers in 1980’s)

High Risk of Noise Induced Hearing Loss

• Industrial/Workplace

• Military

• Recreational Noise Exposure

• Musicians

Common Noise

Sources

Waste extraction Fan

Electric motor

Air Compressor

Assembly machine Ultrasonic welder

Music Induced Hearing Loss

• Hearing loss due to excessive, unprotected exposures to loud music Listening to an MP3 player at full

volume for one hour a day is enough to seriously damage people's hearing

Attending a rock concert

Florence Nightingale wasn’t exaggerating when she referred to hospital noise as “abuse.”

Florence Nightingale wrote in her 1859 book, Notes on Nursing

she wrote, “Unnecessary noise is the most cruel abuse of care which can be inflicted on either the sick or the well.”

World Health Organization’s recommendation of 35 decibels as a top measure of sound levels in patient rooms.

medical and communications technologies - major culprits behind increasing noise levels. Communications devices like overhead pagers and cell phones - monitoring and life-sustaining equipment continually beeps and whooshes around patients’ beds, occasionally erupting into alarming warning signals

Non-Auditory Effects

• Annoyance

• Sleep Disturbance

• Attention

• Stress reactions

Cardiovascular problems Endocrine problems

Exposure to sudden, unexpected noise raises patient heart rates and has been proven to have a negative influence on patient recovery times. Chronically high levels of sound -tend to increase blood pressure levels

Disrupt sleeping pattern of the neonates

Auditory Effects

• Acoustic Trauma: Sudden hearing damage

• Tinnitus: Ringing in the Ears

• TTS:Temporary threshold shift

• PTS: Permanent threshold shift

NOISE INDUCED HEARING LOSS

Acoustic trauma- Sudden impulsive sound for shorter duration-explossive blast injury

• Progressive

• Can be temporary or permanent – Temporary Loss: Change in hearing after noise exposure but returns in time

– a temporary loss of hearing after exposure to sound---results in a temporary shift of the auditory threshold known as a temporary threshold shift (TTS).

– Permanent Loss: Change in hearing after noise exposure but will NOT return

– The damage can become permanent (permanent threshold shift, PTS) if sufficient recovery time is not allowed for before continued sound exposure

Hallowell Davis’ classic experiments in the 1940s further linked the hair cell damage to hearing loss and he also reported cochlear neuron degeneration and capillary vasoconstriction as a consequence of hazardous noise exposure.

minor bending of the stereocilia (inner ear) is associated with temporary hearing loss and is involved in auditory fatigue. Complete loss of the stereocilia causes permanent hearing damage

NIHL-Dependent on intensity ,duration and type of noise expossure

The greater the intensity of the noise , the less expossure time required for damaging effects Impulsive noise ----physically break hair cells with the potential for little or no recovery Steady state noise (factory noise)—may temporarily stress the hair cells, which then recover after a period of rest

Sound Level

(dBA)

Permitted Duration per

Workday (hours)

Sound Level

(dBA)

Permitted Duration per

Workday (hours)

90 8.00 103 1.32

91 6.96 104 1.15

92 6.06 105 1.00

93 5.28 106 0.86

94 4.60 107 0.76

95 4.00 108 0.66

96 3.48 109 0.56

97 3.03 110 0.50

98 2.63 111 0.43

99 2.30 112 0.38

100 2.00 113 0.33

101 1.73 114 0.28

102 1.52 115 0.25

Table of Permissible Noise Exposure Limits

Why notch at 4 KHz

PREVENTION

Pre-employment & annual examinations Audiometry Designated Factory Doctor

Audiometric screening

Raising Awareness

Sound Level Meter and Noise Dosimeter

Noise monitoring

• noise dosimeters - document the average noise exposure over your working day

A personal noise indicator is a warning device.It indicates if your immediate exposure is less than or greater than 85 dBA. It flashes green if the sound level is under 85 dBA and red when above 85 dBA.

Hearing Protection Devices

Ear Muffs

Advantages

• More protection at higher frequencies than earplugs

• Various NRRs available • Durable, long lasting • Can be fitted on hard hat • Reusable

Some high-tech muffs can filter out certain frequencies or have radios inside for communication in high noise areas

Custom earplugs

– Common option for musicians

– More expensive but are custom

– Earmold Impressions

– Typically are more comfortable and can provide a better seal • Most companies have a choice of either 9, 15, or 25 dB filters on

earplugs

Foam Insert Earplugs

Advantages

• Inexpensive; disposable

• Can be custom molded for individual worker

• Reusable plugs are available

Semi-aural Caps

Ear caps are like earplugs, except they do not go into the ear canal, they only block it. They are good for occasional use or for people who find earplugs uncomfortable. They are not as protective as earplugs or muffs.

• Ideal for people going in and out of noisy areas

Buildings can be designed with suitable noise absorbing material for the walls, windows, and ceilings. Noise Barriers

pre-fabricated noise barriers-Block the noise by building temporary barriers of plywood or other on-site materials to keep the noise from reaching

Soundproof doors and windows can be installed to block unwanted noise from outside.

Regulations should be imposed to restrict the usage of play loudspeakers

acoustical insulation-Place wooden box over the generator. Add fire-resistant acoustical absorbing material (foam) inside the box. If the generator sits on soil or sand,that will help absorb some of the noise.

Similar to automobiles, lubrication of the machinery and servicing should be done to minimize noise generation.

• It is cumulative like tobacco. • One cigarette will not kill you and one day at work will not

make you deaf. • Neither will two or three – but where is the line? It is easy

to say “one more exposure is not going to make any difference.”