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TheBoss TheBoss is offline
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Default Sound Pressure Level Meter Weighting (SPL)

Hi ST,


On May 5, 10:38*am, ST wrote:
Hi to all,

My initial post "Is flat frequencies desirable" did not really answer
what I was looking for . Though it generates a of of interesting point
that never crossed my mind before. Keep it going.

Now perhaps,I will ask the same question from a different perspective?

According to a HIgh End magazine when setting up loudspeaker or tuning
the room it is advisable to use C-Weighting measurement in the SPL. If
my reading of weighting is correct A-weighting reflects perceived
sound more accurately.


If you like the results from using A-weighting, then it must be better
for you than C-weighting.


Sound mixing engineers usually do mixing based on hearing and I doubt
they use SPL to see how loud the bass should be and etc..etc. It all
depends on what they hear. Correct?


I wouldn't presume the methods of mix engineers. In fact, I would
believe that there are many differences in mix engineer methods.
There is likely some care taken to present the engineer with a quality
of sound in the control room that will enable valid decisions to be
made during mixing. Whether this is a flat frequency response, or a
tailored frequency response probably depends on the engineer, the
studio, the producer, etc... I have read and heard that some control
room setups are tuned to a generally typical frequency response that
the mass audience of the material will probably be listening with on
their home stereos, radios, boom boxes, and such.

So, initially I measure the room response level using C-weighting and
with the necessary adjustment so that gives the real measurement. But
the sound turned out to be not to my liking. Then I ignored the SPL
and setup the room and speakers placement according to my ears and I
got the sound right tome the select few who I think understand music
well.


Positioning the speakers, in my opinion is job 1. Finding the best
room loading position where any room modes, resonances are minimized
from muddying up the sound, and never positioning the speakers to
sacrifice good stereo imaging. It is usually a bit of compromise, but
I believe it is always worth the time for experimentation.

Job 2, in my opinion is room treatment or renovation. Adding or
subtracting sound absorbing materials like curtains, drapes, rugs,
bookcases, acoustic wall and ceiling treatments, and such. Adding or
subtracting sound reflective materials like mirror tiles, ceramics,
chandeliers, bookcases, and such.

Sometimes it may require a physical renovation, or adding traps when
dealing with especially troublesome room modes.

The time and work invested in the speaker/room setup usually minimizes
the amount of equalization required, and normally increases the
perception and location of the stereo image througout the room. By
controlling the reflective nature of the room, you also personalize
your own preference regarding realism, to your senses and
expectations.

When the measurement done using SPL and test tone it is found that the
room is now tuned to emphasize the lower frequencies.


This may be a function of your particular room, the speakers, or how
they work together. This may also be a personal expectation in
reproduced sound that you prefer, or find more pleasureable and may
seem more real to your senses.

I personally find that when I am listening to reproduced sound at less
than the original performance SPL, that I prefer some bass boost and a
little high end boost. The human ear drops response in the bass and
highs when listening at lower levels. In fact you may have some
interest in the findings of Fletcher-Munson and their "equal loudness
contours" that describes the general response variations in human
hearing at various sound pressure levels. There is further
development on this topic with an newer ISO standard as well.


So my question is should the room and loudspeakers tuned and placed so
that we get a flat frequencies based on A-weighting (i.e, perceived
loudness to human rather than actual loudness)? If the answer is yes
than was the High End magazine was wrong to ask us to use C-weighting?

Regards,
ST


It is really up to you. When evaluating the appreciation of your own
sound setup, I wouldn't dwell too long on A or C or any weighting
arrangement that is mostly used to measure spl in workplaces or
concerts to figure whether people should need to wear hearing
protection or the band may need to turn down the mains.

If you wish to be accurate to the source, then you need to be very
familiar with the source event to be able to pass even a marginal
evaluation of accuracy. It can be difficult to arrange an A-B
listening test of live sound vs reproduced sound in most people's
listening rooms. Not impossible, but very difficult for most to
arrange.

If you are listening for personal enjoyment, then I say by all means
make it so! Don't worry about conforming to engineering standards.
If you have a predisposition to enjoying your reproduced music with
some bass boost, there is nothing wrong with that. Your taste in
tonal balance may change as life goes on as well. If and when it
does, then indulge yourself. If it sounds more real to you, that is
all you need to be concerned with. When listening for pleasure, make
it pleasurable.

Don.