[Dick Pierce[_2_]]

Multiple people intoned:
I've heard this before, and it always strikes me as odd. A full
symphony orchestra in a hall isn't very loud.
...

You make a very good point. It aint the SPLs that are difficult to
reproduce with orchestral music.

Tou are correct. It is NOT the SPL, it's the amount of AIR that a
symphony in full song can move

The amount of air movement is the SPL.

They really are not the same thing. The amount of air movement would
be the acoustic energy in total. The SPLs would be the amplitude of
the air movement at any given position.

Well, in fact, you're all kinda wrong. It's a quantity
"volume velocity" that determines SPL. To illustrate this
in the speaker sense, at low frequencies, the velocity
is low, so the driver's displacement (the product of excursion
and emissive area of the cone) has to be high to achieve the
same SPL as at a very high frequency, where the velocity is
high, thus the required displacement (again, excursion times
emizzive area) can be correspondingly low. This is why an
itsy-bitsy 1" tweeter can produce as much SPL at 10 kHz with
almost no perceptible motions as a 12" woofer can at 50 Hz
moving 1/2".

A classic illustration of this difference would be headphones.
You can get really high SPLs without a great quantity air
movement.

Actually AT THE EARDRUM, the amount of volume velocity for
a given sound pressure level has to be exactly the same,
whether it's coming from a headphone 1/2" away or a speaker
10' away.

You can get really loud and deep bass from headphones but
you wont feel it in your chest.

Well. it's not so much of a "classic illustration" as a
comparison of apples and oranges. Those headphones also
won't be moving the walls in your room, keeping the
significant other and the neighbors awake, and contributing,
in a very tiny way, to global warming either. So what?

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+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
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