On Sat, 2010-07-24 at 22:31 +0200, [email protected] wrote: > On Sat, Jul 24, 2010 at 02:58:36PM +0200, lieven moors wrote: > > > On 07/23/2010 10:23 PM, [email protected] wrote: > > > On Fri, Jul 23, 2010 at 06:42:11PM +0200, lieven moors wrote: > > > > > > > > >> On 07/23/2010 06:29 PM, [email protected] wrote: > > >> > > >> > > >>> Transporting this to the audio domain, given two similar > > >>> sounds A and B with a B having a higher level than A, you > > >>> could adjust a third one X so it appears to be 'halfway' > > >>> between A and B. If you do this with A much smaller than > > >>> B, would you expect X to be close to 'half a loud as B' ? > > >>> > > >>> > > >>> > > >> If A would be very close to silence, yes. > > >> > > > I'd be *very* surprised if that would turn out to be true. > > > > > > I bet that if B is A + 40 dB, X would turn out to be > > > close to A + 20 dB. And if B is A + 60 dB, X will be > > > close to A + 30 dB. In both cases A is very small > > > conpared to B (at most 1/10000 in power). > > > > > > Ciao, > > > > > > > > Let's put it differently. If you only had sound B, and you > > were asked to position a similar sound X halfway between > > total silence, and the level of sound B, wouldn't that be the > > same as asking that sound X has half the loudness of sound > > B, or as asking that sound B has double the loudness of > > sound X? > > So with e.g. A = B - 60 dB we could end up with X at > B - 30 dB (two steps of 30dB which are supposed to be > near equal subjectively), while with A = silence we would > have X somewhere between -6 and -10 dB relative to B > (these are the extremes of common values for 'twice as > loud'). How low can A be before this inconsistency turns > up ? Or more important: how reliable is such an idea of > 'halfway' ? > > The simple fact is that on a logarithmic scale the whole > concept of 'half' or 'double' is **meaningless**. That is > because such a scale depends on an arbitrary reference > value, and changing that value shifts the whole scale by > a constant amount without changing the underlying reality. > Two levels that are e.g. 10 and 20 on one scale (hence the > second is 'double' the first) could be as well be 80 and 90 > just by changing the reference value for the log scale. > > Of course half/double still makes sense in the original > domain. But if the perceptual scale is logarithmic, they > are perceived as a constant difference, not as a ratio. > > Ciao, >
I had this discussion for the Richter scale. I don't have knowledge of math. Isn't it possible to give a value, e.g. for physics (electrics and optics) there's a value of square root 2. Isn't there such a similar simple value for log scales? _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
