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).


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

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