Ch. 10: Hearing Protection Flashcards
What factors should be considered when choosing and using hearing protection?
When choosing hearing protection, the following factors should be considered: • comfort • the amount of attenuation • ease of use • wearability (i.e., compatibility with other headgear and clothing) • cost • the type of work environment • care and cleaning requirements • sizing and fitting capabilities • the wearer’s personal preferences • the protection’s visibility while being worn • carrying considerations
In Alberta, what is the standard for hearing protectors?
- According to the Alberta Occupational Health and Safety Code, hearing protectors must comply with CSA Standard.
-The Canadian standard that applies to hearing protectors is Hearing Protection Devices – Performance, Selection, Care, and Use. - The Alberta Occupational Health and Safety Code references this standard in Schedule 3, Table 2.
- It is a useful reference for anyone involved in administering the hearing protection component of a noise management program. -It outlines the requirements for protectors including physical characteristics and attenuation requirements
-provides information about selecting and using hearing protectors.
-CSA uses an A, B, C rating system to classify protectors. The classification of hearing protection is based on how much they attenuate (reduce) sound levels at nine different frequencies between 125 and 8000 Hz. The manufacturer of hearing protection must provide this information.
-CSA standard introduced a 0 to 4 grading system for hearing protection devices.
-A device with 0 grading provides the least protection and 4 provides the most.
Most available protection will have information that classifies the protection according to the standard used in the United States and may not include information about whether a protector meets CSA standards.
-The United States uses the Noise Reduction Rating (NRR) system. In this system a particular class is not specified and it does not provide attenuation data comparable to that required by CSA. Instead, it supplies a number value that, theoretically, can be subtracted from the sound level in a particular area to determine whether or not the sound level that results is a permissible level.
-The NRR was designed to be used on the C-weighted scale, and if you have sound levels on the C-weighted scale, use them. For practical purposes, you may use the A-weighted scale. For example, if a protector has an NRR of 22 and the sound level in a work area is 94 dBA, the attenuation provided by the protector should bring the noise level down to 72 dBA, which is within permissible limits.
-Because tests are done in a laboratory under ideal conditions, and because there may be considerable deviation, NRRs should be used as a general guide only. Actual field experience, however, indicates NRR rated devices may provide less than half the attenuation stated in the NRR.
What class of hearing protector is required for noise levels between 100 and 105 dBA according to the Alberta Occupational Health and Safety Code?
To comply with the Alberta Occupational Health and Safety Code, a Class A protector is required.
According to the Alberta Occupational Health and Safety Code, when are both plugs and ear muffs required?
According to the Alberta Occupational Health and Safety Code, section 222 (1), Schedule 3, Table 2, both plugs and ear muffs are required when noise levels are greater than 105 dBA Lex.
Ear Plugs
-placed in or against the entrance of ear canal to form a seal and block sound.
-categorized as foam, push-to-fit foam, premoulded, formable, custom-moulded, semi-insert and semi-aural types.
-most popular plug used is a mouldable ear plug that is made from foam, has a universal fit, and is disposable.
>advantages of mouldable plug are that it expands or contracts to eliminate fitting problems and is the most cost-effective type of protection.
>mouldable plugs provide enough attenuation to classify as a Class A Protector.
>mouldable plugs may be the best protection in hot environments, particularly when other personal protective equipment is used and one requires a small protector that does not interfere with other equipment.
>one pitfall is that care must be taken to insert the plug properly. If not inserted properly, the required attenuation will not be provided.
-pre-moulded ear plugs come in two types: commercial and custom-moulded. >commercially made pre-moulded plugs are made out of vinyl or silicone, are flexible, durable, and can be washed.
>are small and relatively inexpensive.
>different sizes are available, and care must be taken to obtain the proper size and fit for each ear as not every individual has two ear canals that are the same size.
>it has a tendency to loosen during the work day and does so more easily than a mouldable plug; once loosened, the attenuation property is lost.
>pre-moulded plugs of this type can also harden eventually, and they need replacement from time to time.
-Custom-moulded ear plugs are made directly from moulds of an individual’s ear canals.
>cost more than other plugs, but some workers may find insertion easier and the fit better.
>because they are worn for an extended period and are not disposable, extra care is needed to keep the plugs clean on a daily basis.
>custom-moulded ear plugs must be made by skilled professionals and it is important to verify proper fit.
-There are additional considerations during the selection of plugs for hearing protection.
>Plugs may be more comfortable where protection has to be worn for an extended period of time.
>are cooler than muffs in hot environments and may be more practical in confined spaces.
-As with muffs, it is important to check the attenuation provided. The attenuation of plugs can be variable, and the proper fit and insertion of plugs is critical in maintaining attenuation.
-Ear plugs can loosen during chewing and talking and will need to be reinserted periodically.
-In some dusty or dirty work environments, proper hygiene during insertion and re-insertion is difficult to maintain.
-Because of their size and location, plugs are not easily seen by supervisors and, therefore, the wearing of plugs is more difficult to monitor.
Semi-Aural Protectors:
- Semi-aural protectors look like earplugs with a headband.
- They have tips that are either inserted into the ear canals or that cap the ear canals.
- Convenient for short wearing periods when protection is put on and taken off frequently.
- Are not intended to be worn for long periods, particularly in high-noise areas. Their use is generally limited and, therefore, they are not as popular as plugs or muffs.
Ear Muffs:
- Ear muffs are circum-aural protectors with an adjustable headband and plastic cups that fit completely over the outer ears.
- The cups provide a seal against the head by means of cushions that contain either oil or soft foam.
- Different sizes are available, and different designs have headbands to be worn either on top of the head, behind the head, or under the chin. Some are attached to hardhats.
- When using ear muffs, a good seal between the cup and head is critical for providing the required attenuation.
- The seal should completely surround the ear and should provide enough tension against the head without causing discomfort.
- The cushions that are against the head should be inspected frequently for signs of wear and replaced as necessary.
- Ear muffs are easier to monitor than plugs, are more hygienic, and are easier to put on and take off. In addition, muffs provide attenuation that is less variable than plugs. Comfort may be more difficult to obtain because of the necessary headband tension and the increased surface area between the cushion and the head. With proper adjustment and fit, muffs can be comfortable. Workers often find muffs too hot in hot working environments or when extended wear is necessary. Muffs are bulkier than plugs and not as easy to carry. If glasses are worn with ear muffs, the temple bar can interfere with attenuation. Small cushions and temple pads are available and may alleviate the problems associated with having to wear muffs and glasses.
- Earmuffs may also be attached to hard hats. The cups of capmounted earmuffs are directly attached to a hard hat by short arms that are spring-loaded to press the caps snugly against the ears.
Active protection devices:
- Active protection devices usually make use of electronic means to reduce noise at the ear or to enhance the user’s awareness of surrounding activity:
a. Noise attenuating communication headsets – designed primarily for voice- transmission from/to a remote location.
b. Hearing protection devices with direct music input – for direct connectivity with personal listening devices. The sound exposure experienced by the user is the combination of the external noise passing through the device or around the seal of the device, and the music emitted.
c. Active noise reduction (ANR) hearing protection devices – available in both earmuff and earplug types; use the destructive interference properties of out- of-phase sound waves to reduce the ambient noise at the ear.
d. Sound restoration hearing protection devices – designed to improve speech intelligibility and auditory perception in situations where high noise levels alternate with quiet periods. A microphone captures the sound outside the protector, which is then amplified and fed inside the earcup or earplug.
Passive protection devices:
- the attenuation characteristic is altered by mechanical means to achieve a desired level of performance.
a. Flat or uniform attenuation – incorporate devices such as a sound channel and resonator or a diaphragm located in the channel, that provide a nearly linear attenuation between frequencies of about 200 and 4000 Hz. As a result sound is perceived as more natural without the muffling effect of the reduced high- frequency levels typical of conventional hearing protection devices (HPD).
b. Frequency-sensitive protectors –intended to improve communication by allowing predetermined noise frequencies through the HPD while stopping others.
c. Adjustable-attenuation protectors –intended to achieve a good compromise between protection and overprotection in a given noise environment.
d. Amplitude-sensitive or level-dependent protectors – provide low attenuation at low noise levels but increase the protection as the noise levels rise.
Hearing Protection Standards:
- The Canadian standard that applies to hearing protectors is Hearing Protection Devices – Performance, Selection, Care, and Use, [(OHS Code, Part 16, Section 222(1)]. The Alberta Occupational Health and Safety Code references this standard (Schedule 3, Table 2).
- A reference for anyone involved in administering the hearing protection component of a noise management program.
- It outlines the requirements for protectors including physical characteristics and attenuation requirements, and it also provides information about selecting and using hearing protectors.
- CSA uses an A, B, C rating system to classify protectors. The classification of hearing protection is based on how much they attenuate (reduce) sound levels at nine different frequencies between 125 and 8000 Hz (manufacturer must provide this information).
- The CSA standard has introduced a 0 to 4 grading system for hearing protection devices. A device with 0 grading provides the least protection and 4 provides the most.
- Most will have information that classifies protection according to standard used in the United States (may not include information about whether it meets CSA standards).
- The United States uses the Noise Reduction Rating (NRR) system. In this system a particular class is not specified.
- The NRR does not provide attenuation data comparable to that required by CSA. Instead, it supplies a number value that, theoretically, can be subtracted from the sound level in a particular area to determine whether or not the sound level that results is a permissible level.
- The NRR was designed to be used on the C-weighted scale, and if you have sound levels on the C-weighted scale, use them. For practical purposes, you may use the A-weighted scale. For example, if a protector has an NRR of 22 and the sound level in a work area is 94 dBA, the attenuation provided by the protector (if worn properly) should bring the noise level down to 72 dBA, which is within permissible limits. Because tests are done in a laboratory under ideal conditions, and because there may be considerable deviation, NRRs should be used as a general guide only. Actual field experience, however, indicates NRR rated devices may provide less than half the attenuation stated in the NRR.
