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 <[email protected]> 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 > > > _______________________________________________ > Linux-audio-dev mailing list > [email protected] > http://lists.linuxaudio.org/listinfo/linux-audio-dev > >
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