Re: [LAD] twice as loud

From: Frank Smith <frsmith@email-addr-hidden>
Date: Fri Jul 23 2010 - 13:13:08 EEST

Hi All
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.

Cheers
Bob

On 22 July 2010 20:14, lieven moors <lievenmoors@email-addr-hidden> wrote:

> On 07/21/2010 07:24 PM, Fons Adriaensen-2 wrote:
>
> 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).
>
>
> Hi Fons, I'm a fool to even try to answer this question.
> But I couldn't resist...
>
> Let's suppose we have two sounds A and B,
> and sound B has been measured as being twice as loud as A,
> by somebody. In order to be able to say that, that person needs
> some kind of reference measurement unit, the equivalent of a
> measurement stick. That unit has to satisfy two requirements.
> It has to be big enough, so that people can agree some difference
> is being measured, and it has to be small enough, so that a multiples
> of that unit fit into a realistic range. There is a requirement of maximum
> precision (the smallest value we can measure), and a requirement of
> minimum precision. The question is, what kind of measurement stick
> is being used by that person.
>
> First of all, we can assume that the length of that stick will be depend
> on the range of possible input values that we observe, and that we want
> to measure. If we want to measure the size of a road, we will probably
> use kilometers, instead of meters. In the same way, when our ears want
> to measure the amplitude of a sound, our ears will use smaller or bigger
> units, depending on the ranges observed. What are the ranges we observe?
> Let's assume that humans are perfect, and observe everything that we
> can observe with SPL meters. We could do a statistical investigation
> on a number of people, and make charts of everything they hear.
> In these charts we would see what frequencies they are exposed to,
> and what the minimum and maximum SPL's are for that frequencies.
> After more analyses, we would have one chart that could be
> representative for most people.
>
> From that chart we could get an estimate of the size of the measurement
> unit. Frequencies with with bigger SPL variations would be measured
> with bigger units, and visa versa. And from this we could deduce what
> the minimum precision is for a certain frequency, when we say it is twice
> as loud. To satisfy the requirement of maximum precision, we should
> take into account the smallest observable differences for every frequency
> in the spectrum.
>
> now you can kill me :-)
>
> Greetings,
>
> Lieven
>
>
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Received on Fri, 23 Jul 2010 11:13:08 +0100

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