Both OSHA (Occupational Safety & Health Administration) in the U.S. and CCOHS (Canadian Council for Occupational Health & Safety) have similar recommendations for both the types and use of hearing protection devices. They state that the necessity of ear noise protection depends primarily on

• The level of the noise to be eliminated.
• The nature of the noise, sustained or intermittent.
• The work responsibilities and comfort of the person wearing ear protection.

For instance, both agencies recommend the use of hearing protection equipment if you are surrounded by sustained noise levels of more than 85 to 90 decibels during an eight hour day. As the workplace noise level rises, the allowable time period to go without ear plugs or muffs is reduced. For example, if you’re exposed to sustained noise for four hours at a decibel level over 95 dB, you should wear the best hearing protection available.

OSHA further states that “ Hearing protectors worn by employees must reduce an employee’s noise exposure to within the acceptable limits noted in Table 5.” (Table 5 in the OSHA info booklet is the illustration that shows acceptable noise duration at various decibel levels). The question of whether to use the best earplugs or hearing protection muffs depends on how long the noise is sustained, the usual movements by the worker around the worksite, and the overall comfort level of the employee.
For example, let’s assume you are exposed to a jackhammer, producing 105 decibels, but it is only used intermittently and not constantly. Wearing custom earplugs, embedded in your ears, might prove to be cumbersome to insert, remove, re-insert, etc. A good set of ear protection muffs may be much more convenient to use in this situation. The bottom line, per OSHA, is to recognize when hearing protection is needed and to ensure that the solution you choose reduces the noise level to, at least, under 85 to 90 dB.