Big_Ham

iTrader: (1)

I emailed your exact quote to my entire car stereo team, and the two best answers are below. The one directly below is the REAL answer (and it appears we were both 33% correct) and the one below that shows the REAL confusion over this subject - the owner of MMXPress, like myself, has been partially mislead (not told the whole story that Danny Holdman tells directly below). So in any event, my hats off to your mathematical equation ...
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Actually, it is a logarithmic scale. Mathematically speaking, twice as loud would be, as Eddie said, 10dB difference. The problem is that there is no absolute reference. The 'base' of 0dB is defined as the limit of human hearing, which, as we all know, is different for everyone. A decibel is actually 1 tenth of a Bel (named for Alexander Graham Bell). A 1 Bel difference is a doubling (logarithmic scale) of sound pressure, when two sounds are taken in comparison to one another. Thus, a decibel (deci = 1x10-1) is one 10th of that value.
"Just as with frequency, humans notice changes in loudness logarithmically. Although an increase of 6 dB SPL is a doubling in air pressure, humans do not
perceive a doubling in loudness unless the pressure is increased by 10dB SPL. So an increase in pressure of 10 dB SPL is to perceived change in volume
what a doubling of frequency is to perceived change in pitch." (I don't know who wrote this page, but it is very informative - http://www.gozen.demon.co.uk/godric/sound/fbel.html ).

If you really want to know, go do a search on the net for Bel, decibel, sound, and volume. You can come up with a ton of information, most of which is very accurate and helpful.

Where ppl get that 3dB is 'twice' as loud is because if you double power or cone area, in theory you will get a 3dB gain. Hence they think that 3dB is 'twice as loud', but strictly mathmatically speaking it is not twice as loud until a 10 dB increment is reached.

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|"John Spagnolo - MMXpress.com" wrote:
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|3 dBs is double, period.Its an exponential scale. so 80 dbs is twice |as loud as 77 dBs, 83 dBs is twice as loud as 80 dBs but FOUR times |as loud as 77 dB. Nobody would argue that 140 dBs is more than twice |as loud as 70, right?I think they say the human ear needs between a |6 and 10 dB increase to have it SOUND twice as loud. So the |perceived doubling in volume, and the true doubling, are maybe not |the same thing, but he is dead wrong.
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|John - Multi Media Xpress /Car Stereo Pro www.mmxpress.com
|9-11-01 - Never forget. God Bless America.

iansw

iTrader: (7)

Ummm.

The theories thay are relating to have alot more to do with Frequencies than decibels.

Audio Engineers they are not. Of course decibels are about perception. So is space, and time.

What they're saying is incorrect in the fact that space, time, and decibels are a measurement that is a scientific standard. 6db is not "perceptively" twice as loud, it IS twice as loud as measured by a decibel meter, which measures the loudness by decibels, and is accepted as a logical and MATHEMATICAL measurement by the scientific community.

What I percieve as 10 feet, for instance, you may percieve as 8 or 12 feet. When we pull out the measuring tape, whatever that distance really is is what it REALLY is, as accepted by the scientific community and the human race at large.

Maybe in the 5th dimension 10 feet here is really 5 feet there....but I haven't found a wormhole to get there yet.

Same in this case. +3db is twice as loud. Whether you percieve it as that or not. It's measured using a formula. It's math, it's science, it's logic.

IanS

Big_Ham

iTrader: (1)

You'd probably get a kick out of the argument I started. Eddie Runner (owner of River Oaks Car Stereo, www.installer.com) is arguing with John from MMXPress.com amongst many other people. You need boxing headgear just to reply to one of their emails. Very scientific tho, you would probably be impressed with the overall conversation.