Occupation Noise Flashcards
Define sound and noise
Sound
- objective - pressure fluctuations detected by human ear
- subjective: any sensation of sound
Noise is unwanted sound, unpleasant, undesired by the recipient
What is the decibel halving rule
A 3 dB increase will double the sound pressure level.
Double the intensity means halve the time you can be exposures 85. = 8 hours 88. = 4 hours 91. = 2 hours 94. = 1 hour 97 = 30mins 100 = 15mins
2 conduction pathway
Air conduction
- transmission along acoustic pathway
Bone conduction
- direct stimulation of cochlea by vibration
- physical vibration or loud sounds
- some protection from helmet
How does noise degrade performance and safety
Psychological impact stress and distraction Degraded communication Hearing loss, temporary or permanent Fatigue Increased workload
Fluctuation of HR, RR, BP Increased anxiety Decreased GI motility Alter regional blood flow Vertigo Disorientation Vomiting
Describe temporary vs permanent hearing losing and the difference
Temporary threshold shift
- acute exposure
- Muffled hearing
- tinnitus
- Rapid recovery
Noise induced hearing loss
- continued exposure
- high tone loss
- usually bilateral
- Irreversible
Factors affecting NIHL
individual susceptibility Age Nature of noise: continuous/intermittent/impact Noise intensity Duration Protective devices used Continual and correct use of PPE
Way to improve communication
Noise - attenuating headsets Noise- canceling microphones Radio procedures - phonetic alphabet - standard phraseology
Psychological effects of noise
More harmful
- intermittent noise
- impulsive noise
- high frequency noise
- relevant noise
- prolonged exposure
Less harmful
- continuous noise
- low frequency noise
- irrelevant noise
- short-term exposure
More vulnerable tasks
- continuous task, prolonged vigilance, multi-tasking, auditory tasks
Les vulnerable task
- intermittent task, simple repetitive task, non-auditory tasks, physical exercise
More vulnerable people - introverts
Less vulnerable people - extroverts
Clinical assessment
Audiogram - if average loss > 15dB at any frequency - inform the employee - check noise exposure history - check suitability/condition/fitting/use f HPD - re-issue HPD f required - retest in 6 months Duty of care consideration
Types of hearing loss
Industrial hearing less
- peak at 4000Hz
Age related changes - Presbyacusis
- ???
Infection - conductive hearing loss
What is equivalent noise level
The overall noise within a measurement time interval expressed as single numbers
Permissible daily exposure duration
Maximum period for which a person can be exposed without exceeding the OH&S limit for occupational noise.
Doesn’t take into account exposure when not at work
What is the safe level of noise
Australian standard
Continue noise 85dB over 8 hours
Peak noise 140dB
Only reduces risk to <5%
Aviation noise levels
Commonly 120-130 dB
Therefore required protection of 45dB
Sources of noise around Military aviation
Aerodynamic noise Engine noise Environmental conditioning systems Avionics and avionics cooling Weapon systems Auditory warning systems Communication
Factors affecting noise
Aircraft type Altitude speed - lower you fly the noise it is Aircraft design Ancillary systems Aerodynamics Avionics Communication, audible warmings Weapons Accommodation Proximity of ground personnel
Protection from noise
Engineering of control
- elimination
- enclosure
- isolate
Administrative control
- work scheduling
- job rotation
- Quiet work practices
- restricted areas
Personal protection
- Hearing protection devices
Hearing protection devices
Ear muffs Ear plugs - standard, communication or custom moulded Ear caps Electronic cancellation of noise Covering head and ears - helmet Single or in combination
Active noise reduction
Reverses frequency?
Considerations in selecting HPD
Compliance with AS 1270 Provides adequate attenuation by avoids over- protection Communication requirements Comfort and wear time Compatibility with workplace Combing HPDs if required medical factors
Hearing protection areas and and protection required
Amber 85–100, impulse 140-150 - ear muff or plug
Red 100-115 impulse 150-160 - ear muff
Black 115-120. Impulse 160-166 - Earmuff +plug
Extreme >120 impulse >166 - Earmuff +plug + time
Audiogram requirements
Amber, red, black - initial then annually, on request and at termination
Extreame - initial, six monthly, on request and at termination.
Noise induced hearing loss
A. Usually improves over time
B. Is a conductive hearing loss
C. Is centred around the 4kHz frequency band
D. Is an uncommon cause for compensation claims
C. Is centred around the 4 kHz frequency band
