Hi All<div>I was under the impression that every 3 db increase doubled the volume and you needed to increase the power needed by a factor of 3 . Things could have changed by now but this is what I use.</div><div><br></div>
<div>Cheers</div><div>Bob</div><div><br></div><div><br></div><div><br></div><div><br><div class="gmail_quote">On 22 July 2010 20:14, lieven moors <span dir="ltr"><<a href="mailto:lievenmoors@gmail.com">lievenmoors@gmail.com</a>></span> wrote:<br>
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On 07/21/2010 07:24 PM, Fons Adriaensen-2 wrote:
<blockquote type="cite">
On
Thu, Jul 22, 2010 at 01:05:01AM +0200, Philipp Überbacher wrote:
<br>
<br>
> I think the word loudness is a problem here. Afaik it usually
refers to
<br>
> how it is perceived, and twice the amplitude doesn't mean twice
the
<br>
> perceived loudness. It may mean twice the sound pressure level,
energy,
<br>
> or intensity (if we ignore analogue anomalies, as you wrote in
some other
<br>
> answer).
<br>
<br>
Subjective loudness is a very complex thing, depending on the
<br>
spectrum, duration, and other aspects of the sound, and also
<br>
on circumstances not related to the sound itself.
<br>
<br>
For mid frequencies and a duraion of one second, the average
<br>
subjective impression of 'twice as loud' seems to correspond
<br>
to an SPL difference of around +10 dB. <br>
<br>
I often wondered what criterion we use to determine which <br>
objective SPL difference sounds as 'twice as loud'. We don't
<br>
have any conscious numerical value (there may be unconscious
<br>
ones such as the amount of auditory nerve pulses, or the amount
<br>
of neural activity), so what it this impression based on ?
<br>
<br>
The only thing I could imagine is some link with the subjective
<br>
impression of a variable number of identical sources. For example
<br>
two people talking could be considered to be 'twice as loud' as
<br>
one. But that is not the case, the results don't fit at all (it
<br>
would mean 3 dB instead of 10).
<br>
<br>
</blockquote>
<br>
Hi Fons, I'm a fool to even try to answer this question.<br>
But I couldn't resist...<br>
<br>
Let's suppose we have two sounds A and B, <br>
and sound B has been measured as being twice as loud as A,<br>
by somebody. In order to be able to say that, that person needs <br>
some kind of reference measurement unit, the equivalent of a <br>
measurement stick. That unit has to satisfy two requirements. <br>
It has to be big enough, so that people can agree some difference <br>
is being measured, and it has to be small enough, so that a multiples<br>
of that unit fit into a realistic range. There is a requirement of
maximum <br>
precision (the smallest value we can measure), and a requirement of <br>
minimum precision. The question is, what kind of measurement stick <br>
is being used by that person.<br>
<br>
First of all, we can assume that the length of that stick will be
depend <br>
on the range of possible input values that we observe, and that we want
<br>
to measure. If we want to measure the size of a road, we will probably <br>
use kilometers, instead of meters. In the same way, when our ears want<br>
to measure the amplitude of a sound, our ears will use smaller or bigger<br>
units, depending on the ranges observed. What are the ranges we observe?<br>
Let's assume that humans are perfect, and observe everything that we <br>
can observe with SPL meters. We could do a statistical investigation<br>
on a number of people, and make charts of everything they hear.<br>
In these charts we would see what frequencies they are exposed to, <br>
and what the minimum and maximum SPL's are for that frequencies.<br>
After more analyses, we would have one chart that could be <br>
representative for most people.<br>
<br>
>From that chart we could get an estimate of the size of the measurement
<br>
unit. Frequencies with with bigger SPL variations would be measured <br>
with bigger units, and visa versa. And from this we could deduce what <br>
the minimum precision is for a certain frequency, when we say it is
twice <br>
as loud. To satisfy the requirement of maximum precision, we should<br>
take into account the smallest observable differences for every
frequency<br>
in the spectrum.<br>
<br>
now you can kill me :-)<br>
<br>
Greetings,<br>
<br>
Lieven<br>
<br>
</div>
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