Monitor SPL vs. Full-Range SPL

If I am not mistaken I believe white noise is used when a speaker's SPL in dB/M is measured. This means the speaker level are equal at any frequency its capable of.

I think you are confusing sensitivity and SPL. SPL is nothing more than a unit. Either the speaker in question can produce a certain number of units or it can't.

80 db is 80 db regardless of the speaker producing it.

There are some stand mount speakers that because of their drivers and design are capable of more bass output than some floor standers. How much power it takes to get there is a different situation, and that's where sensitivity comes into play.

I'll add only this, as freq's go down, you won't hear them as louder...probably, you won't hear them at all.

Deep bass is felt more than heard.

Dave

The point is, if a speaker has increased bass output because of increased FR range overall SPL will be higher. Consider this, if speakers are set to 80 db playing a 1kHz test tone, SPL will not be the same when playing white noise since the full range speaker plays deeper in the bass (audible or not, it will still measure on an SPL meter).
I am thinking bright speakers will be played quieter since subjectively they sound louder since bass notes are not heard but more felt.

The main problem with high SPL level is that it requires costly drivers that do not compress or exceed Xmax easily....this is expecially true in the bass and cost goes up almost exponentially as one desires high SPL at low distortion in the bass. However, this is rarely a criteria for consumer audio where levels are usually modest and do not have to playback music at realistic levels to artists/musicians or survive accidents such as a dropped microphone or as mistake in a patch panel.

Hi CDC, You are correct and what you are driving at is very important. If you are listening to your system at a reference signal of 83db at 1000hz and your system goes to 50hz the overall SPL of white noise (or music) will be less than if your system is capable of 20hz. 80db is most definatly not 80db for every speaker, for a white noise response. 1000hz is 1000hz for every speaker, but depending on the speakers freq response and the rooms ability to reproduce the rest of the freq spectrum, that is the rest of the story.

Who says you can't hear 20hz?

This is why I reccomend a specific listening level, that being 83db at 1000hz and tryng to get as flat and as low a freq response as possible as your system is capable of at this level.
Bob

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

Are you confusing loudness with measured SPL? 83dB is 83dB regardless of the frequency.

Although your source may be white noise, and likely to stay pretty white through good electronics, what you measure with a sound pressure level meter from you speakers is almost certainly not white. Spectral level refers to level per frequency, and measures of spectral level, more likely to be measured as 1/3 octave bands, can be expected vary widely as the speaker interacts with its environment or rolls off in sensitivity.

Hearing damage occurs most at a half octave above the assault. Even frequencies to which we are not sensitive shake the basilar membrane, so high-level low-frequency sounds can definitely damage your hearing. It's not perceived loudness, but how hard the hair cells along the membrane are driven. Gun shots are notorius for damaging hearing.

So I think the answer to the OP is that for a given broadband SPL that was sourced with white noise, monitors are likely to seem louder than full range speakers that "squander" energy in the lowest octaves to which we are not very sensitive. But those of us who love pipe organs, do so value that squandered energy.

db