Monitor SPL vs. Full-Range SPL

Thanks Acoustat6 for getting what I was trying to say. Here's another novel thought.
I am thinking people have a "reference" volume level which is set at the ear's most sensitive frequency. This is ~3,000 hz I think and is the x-over point for many speakers. If someone listens at 90 dB, it would be 90dB at that frequency.
I know my B&W's have a 8+ dB spike at 3-5,000hz and that spike limited how loud I would listen. See, 80dB overall actually gave me 90dB at 3-5,000hz and that was too loud to my ears. So I usually listened at 70dB to keep that spike at tolerable levels.

Cdc,

Indeed your hearing is most sensitive from 1 to 4 Khz...therefore sounds in this band will determine how loud you can stand it.

120 db SPL at 20 Hz is acceptable to your ears (your body feels most of it and ears are not that sensitive at this frequency)

120 db SPL at 1 Khz is definitely too loud to stand at a continuous level...even occaisional peaks at 120 db spl is starting to seriously push it for your ears (listening damage would ensue if you did this for an extended length of time)

Shadorne, that is interesting. The experts say SPL is what damages the ears but I agree more with what you are saying. From what I remember, the experts say all that bass you hear thumping in cars will damage your ears. But I think the serious flaw in this common knowledge is how high frequencies can damage the ears even at moderate volume SPL's.
Why?
I don't think a 1-4 kHz tone really puts out much SPL compared to a 20 hz tone. So when you start hitting 80-90 db at 1kHz, THAT is some serious volume.
It's too bad the experts don't make this more clear as damage to hearing has less to do with white noise / full range SPL's than all the hype would lead us to believe.

See this Equal Loudness. It is clear that 120 db SPL at 20 Hz is equivalent in loudness to 85 db SPL at 500 to 4 Khz (the mid range). Clearly there is a huge difference in our hearing sensitivity across the audible frequecny range (remember that decibels are logarithmic)

Also note that volume level tends to influence the presentation, as you go up in volume our hearing sensitivity is flatter with respect to frequency.

In practice, this means that rock music that is supposed to be played loud will be mixed a little lean in the bass whilst ambient or acoustic stuff intended to be listened to at low volumes will be mixed with more bass. (this compensates for our hearing non-linear response with respect to volume level)

Here is a good start to help understanding play back levels. Including testing level and reasons for that level.
http://replaygain.hydrogenaudio.org/calibration.html
Bob