22 Jul
2010
22 Jul
'10
3:20 p.m.
On 07/22/2010 05:31 AM, Philipp Überbacher wrote:
Excerpts from Philipp Überbacher's message of
2010-07-22 03:16:00 +0200:
I had a brief look at the section about loudness in musimathics and it
mentions 10 dB based on the work of Stevens, S.S. 1956,
"Calculation of the Loudness of Complex Noise" and 6 dB based on
Warren, R. M. 1970,
"Elimination of Biases in Loudness Judgments for Tones.".
I think I've encountered the 6 dB more often in texts, which doesn't
mean it's closer to the truth, if that's possible at all.
Knowing a 'correct' number would be nice for artists and sound
engineers, but if it varies wildly from person to person, as Gareth Loy
suggests (no idea where he bases this on) then this simply isn't
possible. Picking any number within or around this range is probably as
good as any other.
the
I think this is a very interesting idea. Could this be linked to some
kind of
avarage SPL of all the sounds human beings are exposed to (and this variable
changes throughout history). Because when we try to judge the distance of
a barking dog, our brain would use the knowledge of all other dogs we heard
barking before, to estimate the distance of that dog. If we never heard
a dog
before, maybe we would use the sounds of other animals as a reference,
and so on...
greetings,
Lieven
Excerpts from fons's message of 2010-07-22
02:24:04 +0200:
> On Thu, Jul 22, 2010 at 01:05:01AM +0200, Philipp Überbacher wrote:
>
> > I think the word loudness is a problem here. Afaik it usually
refers to
> > how it is perceived, and twice the
amplitude doesn't mean twice the
> > perceived loudness. It may mean twice the sound pressure level,
energy,
> > or intensity (if we ignore analogue
anomalies, as you wrote in
some other
answer).
Subjective loudness is a very complex thing, depending on the
spectrum, duration, and other aspects of the sound, and also
on circumstances not related to the sound itself.
For mid frequencies and a duraion of one second, the average
subjective impression of 'twice as loud' seems to correspond
to an SPL difference of around +10 dB. I often wondered what criterion we use to
determine which
objective SPL difference sounds as 'twice as loud'. We don't
have any conscious numerical value (there may be unconscious
ones such as the amount of auditory nerve pulses, or the amount
of neural activity), so what it this impression based on ?
The only thing I could imagine is some link with the subjective
impression of a variable number of identical sources. For example
two people talking could be considered to be 'twice as loud' as
one. But that is not the case, the results don't fit at all (it
would mean 3 dB instead of 10).
I never thought about that to be honest. It's immensely complex. It
might have to do with each persons hearing capabilities, for example bandwidth of loudness perception or the smallest
discernible loudness
difference. If it really is very different from person to person, then
an explanation that takes the different hearing capabilities into
account could be sensible, don't you think?
I did find some more approaches to the problem, but those are just
ideas. From my personal experience I have to say that I have a very hard
time saying when something is twice as loud. A musically well trained
person might have an easier time, I wouldn't know, but for me twice as
loud is something that is very vague. This might already explain the
large deviation between subjects as described in musimathics. It lead me
to another idea though, the evolutionary perspective. Evolutionary it
likely never was important whether a sound is twice as loud. The only
situation I can imagine where judging loudness probably was important
is judging distances. How far is the animal I can't see, be it prey or
predator, away from me? We know that this takes more than the SPL into
account, and 'twice as loud' doesn't have relevance in this context. So
maybe the loudness perception is linked with spatialization.
My other ideas are rather stupid, just ways to get the right numbers for
your two person idea.
I simply used ln instead of log and got 7, but that's not even Neper and
has no relevance.
The other idea of that kind is to assume a field quantity, which would
result in 6 dB. I'm still easily confused about 10*log and 20*log, but I
think 20*log is usually used for sound pressure, but maybe not for
psychoacoustic effects.
--
Regards,
Philipp
--
"Wir stehen selbst enttäuscht und sehn betroffen / Den Vorhang zu und
alle Fragen offen." Bertolt Brecht, Der gute Mensch von Sezuan
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