i got a SPL meter awhile back.
ran a "cd of freq's" had the meter attached to a mic stand (where my head/ears would be).
jotted down with pencil and pad the readings for each freq. or SPL/DB values....
it was a beginners type test many said, but was a good hands-on lab for better understanding alot of this jargon.
the pro's studios and physics guys kept saying "mixing at 85db is standard"
etc.. supposedly 85db is the volume where all freqs are equal.
many said the meter and test was bllsht...but when i turned up the treble or bass freq pot on my speakers the meter read it.
some people tune a guitar with their ears, some with an old fashioned tuning fork, some with digital tuners....its this same gearhead stuff, whatever gets you thru the night.