49 CFR §227.115

1. (a)General requirements for hearing protectors.
   1. (1)The railroad shall provide hearing protectors to employees at no cost to the employee.
   2. (2)The railroad shall replace hearing protectors as necessary.
   3. (3)When offering hearing protectors, a railroad shall consider an employee's ability to understand and respond to voice radio communications and audible warnings.
   4. (4)The railroad shall give employees the opportunity to select their hearing protectors from a variety of suitable hearing protectors. The selection shall include devices with a range of attenuation levels.
   5. (5)The railroad shall provide training in the use and care of all hearing protectors provided to employees.
   6. (6)The railroad shall ensure proper initial fitting and supervise the correct use of all hearing protectors.
2. (b)Availability of hearing protectors. A railroad shall make hearing protectors available to all employees exposed to sound levels that meet or exceed the action level.
3. (c)Required use at action level. A railroad shall require the use of hearing protectors when an employee is exposed to sound levels that meet or exceed the action level, and the employee has:
   1. (1)Not yet had a baseline audiogram established pursuant to § 227.109; or
   2. (2)Experienced a standard threshold shift and is required to use hearing protectors under § 227.109(h).
4. (d)Required use for TWA of 90 dB(A). The railroad shall require the use of hearing protectors when an employee is exposed to sound levels equivalent to an 8-hour TWA of 90 dB(A) or greater. The hearing protectors should be used to reduce sound levels to within those levels required by appendix A of this part.