When the application of means for controlling sound at source
does not reduce the noise level in any space to that specified in paragraph 4.1.3, seafarers who
are required to enter such spaces shall be supplied with effective
hearing protection on an individual basis. The provision of hearing
protectors shall not be considered to be a substitute for effective
noise control. Appendix 3 summarizes
current noise abatement methods which may be applied on new ships.