NoiseNoise

Q13What symptom is experienced by those who have tinnitus?

a. Difficulty in hearing low-frequency soundsy g q y

b. Constant dull earache

c. Ringing or buzzing sound in the head

d. Sharp pain in the eard. Sharp pain in the ear

e. Total deafness

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Q14Why is noise-induced hearing loss permanent?

a. Causes eardrum to rupturep

b. Cause degeneration of the auditory nerve

c. Destroys hair cells in the Organ of Corti

d. Produces fine cracks in the delicate bones of thed. Produces fine cracks in the delicate bones of the middle ear

e. Produces severe inflammation of the auditory canal

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y

Q15Which recreational activity, performed for two-hours, is most likely to cause a noise-induced hearing loss?

a. Attending a rock concert

b. Listening to music with head phones

c. Riding motorcycles without a helmet

d. Target shooting

e. Attending class

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g

Noise Overview

Structure & Function of Hearing

Definition

Properties

Regulation

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Regulation

The Hearing Mechanism

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What happens if …

a mime falls in the woods and there is no one to hear him?

Does he make a noise?Does he make a noise?

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What is Noise?Psychological View: Unwanted or useless sounds in the environment

Physical View: All sounds

Limits Based on EffectsDamage to hearingDamage to hearingMasking of desirable soundsAnnoyance and fatigue

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Properties of Sound I

Sound Waves

pressure deviationsth t th h ithat move through air

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Properties of Sound II

Frequency = Number of Waves per SecSingle Frequency Perceived as a ToneSingle Frequency Perceived as a ToneReported as Hertz (Hz)Most Sounds Are a Composite ofMost Sounds Are a Composite of

Frequencies

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Properties of Sound III

Intensity = Pressure Amplitude of the WavePerceived as LoudnessSound Pressure Reported in deciBels (dB)Sound Pressure Reported in deciBels (dB)

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Sound Levels160 dB – Jet engine

140 dB – Pain thresholdPerceived LoudnessDoubles Every 10 dB

120 dB – Riveter

100 dB T k t ffi

y

100 dB – Truck traffic

80 dB – Noisy office80 d o sy o ce

60 dB – Talking Energy On the Ear

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gyDoubles Every 3 dB

Q16Sound is best described by

A. a group consensus of desirability

B d iB lB. deciBels

C pitchC. pitch

D intensity and frequency

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D. intensity and frequency

Hearing Loss

Temporary Threshold ShiftGenerally related to acute exposure (e.g.,Generally related to acute exposure (e.g.,

hunting, concerts)Ringing may be perceivedg g y pMay last several daysRepeated episodes may require hazardRepeated episodes may require hazard

evaluation

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Hearing Loss cont.

Permanent Threshold ShiftSensorineural Damage (Inner Ear)Sensorineural Damage (Inner Ear)IrreversibleRisk is related to life-time exposureRisk is related to life time exposureUsually compared against PresbycusisLosses begin around 4000 HzLosses begin around 4000 HzBWOM Limit = 0.00003 mW/cm2

(1000 Hz for 2000 h/yr)

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(1000 Hz for 2000 h/yr)

Other Effects of Noise

Reduction or Loss of CommunicationsAccidents, quality controlAccidents, quality control

Secondary Health EffectsSecondary Health EffectsStressWork PerformanceWork PerformanceSleep Disruption

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Q17What should drive community noise limits?

A. Potential for hearing loss

B I d t i l dB. Industrial needs

C Personal tastes of city councilC. Personal tastes of city council

D General annoyance

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D. General annoyance

Noise Standards

Sensitivity Depends on Frequency

Measurement Adjusted by FrequencyA S l (dBA)A-Scale (dBA)

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Occupational Noise Standards

Regulatory Agency: Occupational Safety and Health Administration (OSHA)( )Driven by Hearing LossStandards based on chronic and acuteStandards based on chronic and acute

exposure85 / 90 dBA for eight-hour dayg y

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Environmental Noise

Driven by Local and Federal Regulations

LocalC it M i i l R l tiCommunity: Municipal RegulationsLimits on Noise Levels, Sources and

LocationsLocationsTime of Day Limits

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Regulating EnvironmentalRegulating Environmental Noise

Environmental Protection Agency (EPA) Noise Control Act (1972): Established noise limits and

draft legislation for noise related product labeling Quiet Communities Act (1978): Amended the Noise

Control Act, provided for civil penalties and private citizen enforcement procedures, and assistance in developing local regulationsdeveloping local regulations

Dept. of Housing and Urban Development (HUD)Federal Highway Administration (FHWA)Federal Aviation Administration (FAA)Federal Transit Administration (FTA)American Public Transit Association (APTA)

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American Public Transit Association (APTA)

Questions?Questions?