How Do I Find Out the Volume That My Headphones Are At?

I use masking quiet often with the use of ear buds, I have absolutely no clue as to the db level. Is there any way that I can measure this?

 

I as well have always wondered this too. Do different phones output different levels at (1) or (2) ect.? Before my T got worse from a wood saw I listened to mp3 player at moderate volume occasionally, bike riding, pool sitting ect., never had a problem. Now my ears are worse and they seem to be more susceptible and I definitely wouldn't listen to the same volume without knowing.