person will use the baseline noise measurements to assess  the  noise  and  recommend  modifications  if necessary. This is a complex task and may require specialized acoustical instruments. If the ship does not have  access  to  a  formal  noise  assessment,  you  should assume personnel who work in noisy areas are at risk and protect them as well as possible under the guidance of  this  program. In some cases, industrial hygienists may decide that hearing   protective   devices   do   not   give   enough protection  in  a  particular  location.  They  will  then analyze  noise  levels  at  that  location  from  84  dB continuous or intermittent noise to 140 dB peak sound pressure  for  impact  or  impulse  noise.  They  will determine   the   potential   hazard   and   recommend modifications  in  noise  reduction  or  hearing  protection to reduce it. They will resurvey within 30 days after any modification  that  might  alter  the  intensity  of  noise  and recommend  action  based  on  the  results. In areas where there is a strong potential for hearing damage, a medical officer or audiologist will conduct hearing medical surveillance on personnel who work in the areas. They will use their findings to decide if and under  what  circumstances  personnel  may  continue  to work there. They may recommend a reduction in noise, better  hearing  protective  equipment,  or  both. It  may  not  be  necessary  to  apply  all  hearing protection  measures  in  every  case,  but  qualified professionals  using  approved  methods  should  make  that decision. For example, personnel who sometimes enter noise hazard areas may have to wear hearing protective equipment, but they will not need to have their hearing tested. At other times, noise may be intermittent and may not  require  personnel  to  wear  hearing  protective equipment.  These  waivers  must  be  justified  and documented. HEARING TESTS AND MEDICAL EVALUATION All personnel will receive a baseline hearing test when they enter the Navy. The results will serve as a reference for further testing as long as they are in the Navy. Hearing tests done at military entrance stations will not be used for this purpose. Personnel  who  are  assigned  to  duties  in  designated noise hazardous areas or who operate noise hazardous equipment  will  be  included  in  the  hearing  conservation program. An MDR will give these personnel a hearing test annually for as long as they remain in a noise hazardous  environment  and  will  enter  the  results  in  their medical files. The MDR will give additional hearing tests  if  anyone  in  the  program  develops  hearing problems. PERSONAL  HEARING  PROTECTIVE DEVICES Personal  hearing  protective  devices  should  reduce noise  to  a  level  where  it  does  no  harm  to  hearing. However,  only  an  industrial  hygienist  or  other competent   person   can   decide   which   device   or combination is suitable in each noise hazard situation. Normally,  the  correct  devices  will  have  been  selected and they should be available to you whenever you enter designated noise hazard areas. You should wear them at all  times  when  the  noise  sources  are  operating, especially if you are subject to the noise of gun or missile firing. When sound levels exceed 104 dB, you should wear double protection; a combination of insert-type and muff-type hearing protection devices. LABELING  HAZARDOUS  NOISE  AREAS Label all hazardous noise areas and equipment that produce hazardous noise with approved decals or labels. The  labels  are  NAVMED  62602,  Hazardous  Noise Warning Decal (8” x 10-1/2”), NS0105-LF-206-2605, and  NAVMED  6260/2A,  Hazardous  Noise  Label  (1”  x 1-1/2”), NSN0105-LF-21 2-6020. Normally, you should post the outside of doors and hatches leading into a noise hazardous  area,  but  this  does  not  include  weather surfaces. If a noise hazardous area has an entrance from a weather deck post the warning on the inside of the weather deck door or hatch. Do not label exteriors of military combat equipment, but notify the personnel who operate and maintain the equipment about any noise  hazards.  All  hands  are  expected  to  comply  with hazardous  noise  labels  wherever  they  appear. REDUCING NOISE Most work to reduce or eliminate noise will be done when  the  ship  and  its  equipment  are  designed, constructed,  and  tested,  or  following  post-overhaul baseline  surveys.  Any  hazardous  noise  areas  not identified during those times are most likely due to malfunctioning  equipment.  Other  recommendations  for noise  reduction  may  come  from  industrial  hygienists  or other workplace inspections, such as zone, INSURV, ISIC,   or   TYCOM.   The   CO   should   correct   these problems as soon as possible. 10-5