SPL

I found a cheap sound pressure level meter and bought one to adjust my

PA system's loudness at 85dB for mixing work. (80 to 85dB is recommended

in many).

http://www.ecutool.com/SOUND-LEVEL-METER-AR814_4346.html

Then an idea came up to me.

I measured the loudness of my drum kit sound with full strokes.

Here is the results, amazing for me.



  Sound pressure Level      location
 (peak in c-weighting)
----------------------------------------------------------------
   122.5 dB                 drummer's head

   110   dB               in the home studio
                       (2.5 meter away from bass drum reso. head.
                        1 meter away from wall)

     81.5 dB            1 meter away from the wall in the  room next to studio
  ( 50--60 dB)          (background noise. Air conditioner, PC fan etc.)
---------------------------------------------------------------------

Yes, it is very loud for the drummer and indeed we need ear protection.

For example,  Shure SE215 reduces 37dB(at most?).

Then 122.5 - 37 = 85.5 dB is OK for several hours'  drumming practice.

According to an article  http://www.hearforever.org/tools-to-learn/sound-source-a-and-c-weighted-noise-measurements

------------------------------
  Damaging loudness
    90 dB for  8 hours
   100 dB for  2 hours
   115 dB for 15 min
   130 dB pain
------------------------------