Hi guys: Decibels are a measure of the intensity *level* of sound and are an arbitrary scale based on the ratio of the intensity of a given sound with a reference intensity. What does that mean? Well, sound intensity is basically the rate of energy transmitted by a sound wave per unit area. Rate of energy is "power" and is joules-per-second, or "watts". So sound intensity is measured in watts per square meter (W/m^2). Since the human ear/brain is sensitive to a huge range of intensity, a logarithmic scale (decibels) is used to make units more manageable. The average ear can hear sounds anywhere from 1 W/m^2 to 0.000000000001 W/m^2. Once we convert this to decibels it is from 120 dB to 0 dB...a lot easier, huh? Decibels are not a linear measure of perceived "loudness". In other words, a sound of 4 dB doesn't sound twice as loud as a 2 dB sound, nor do two sources of 2 dB add up to 4 dB. In fact there is no direct relation between either decibels or intensity and loudness perception. "Loudness" is strictly psychological and subjective. A system of units for loudness has been developed that involves experimenting with human subjects and asking them which sounds are louder and then correlating them with intensity levels. The unit of loudness is a "sone". A sound of four sones has twice the percieved loudness as two sones, etc. But "how many decibels in a sone" has a different answer for different pitches. A sone is about 70 dB at 60 Hz, but only about 35 dB at 3000 Hz. So there is no simple rule of thumb for loudness in terms of dB. Hope this helps! Don A. Gilmore Mechanical Engineer Kansas City ----- Original Message ----- From: "Robin Hufford" <hufford1@airmail.net> To: "Pianotech" <pianotech@ptg.org> Sent: Wednesday, January 14, 2004 1:04 PM Subject: Re: Software questions MiniMens > Hello Bernhard, > I just came on line to correct my previous post and found your reply. > Thanks. I whipped out that post last evening after just reading a book on > guitar making where it was stated that a 3 Db increase represented a doubling in > loudness. I began to wonder myself afterwards and, having checked with Benande, > found that c. 6 Dbs correspond to a doubling as you say. Apologies to all for > the error. Thanks for clarifying the matter. > Regards, Robin Hufford > > Bernhard Stopper wrote: > > > Definitvely not, Robin. > > there is often confusion with the 3 dB, because 2 added Audio Signals with > > the same dB level will result in a 3 dB higher level. But two same siganls > > do not result in doubling of loudness, a fact that was already known by the > > organ makers. Also 2 strings do not sound as double as one, it raise only ~ > > to1.3 of loudness level. Sometimes you find tables where 10 dB is double > > loudness, that is due to a investigation in the fifties done by Stephens. > > In later investigations (Warren, 1970) has been found that loudness doubling > > is about the 6 dB. But this is also somewhat frequency dependent. > > more info at: > > http://www.personal.rdg.ac.uk/~syswatkn/ap3.pdf > > > > Regards, > > > > Bernhard > > > > ----- Original Message ----- > > From: "Robin Hufford" <hufford1@airmail.net> > > To: "Pianotech" <pianotech@ptg.org> > > Sent: Wednesday, January 14, 2004 9:43 AM > > Subject: Re: Software questions MiniMens > > > > > Actually, I believe 3 Db is about a doubling of "loudness". 3 is a > > > doubling plus 3 more makes a quadrupling plus 3 more makes eightfold at > > > 9 Db. Then 1.5 Db makes approximately tenfold or an order of magnitude. > > > > > > Regards, Robin Hufford > > > > > > Bernhard Stopper wrote: > > > > > > > Part 1.1 Type: Plain Text (text/plain) > > > > Encoding: quoted-printable > > > > > > _______________________________________________ > > > pianotech list info: https://www.moypiano.com/resources/#archives > > > > _______________________________________________ > > pianotech list info: https://www.moypiano.com/resources/#archives > > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives
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